Town Reset?

DivinylsFan​  During a town reset, every sim and lot and object is MC-reset, the same way each one would be if you ran the MC reset commands individually.  Sims are sent to a safe place (home or off the map); objects in use, or stuck seemingly in use, are restored to default, although this doesn't always fix objects stuck in other ways; doors and staircases with existing issues may or may not be fixed; lots have all their objects reset, including any sims or animals that were present.

Additionally, it often happens that objects in sims' inventories are moved to the household inventory, which can be neutral or occasionally very problematic, as with career objects like the pager for cops and doctors.  But you can usually fix this by fiddling with DebugEnabler or just flushing the object and hoping the game provides a new one, which it typically will.

If you want your own sims not to be reset, you can exclude the active lot from town resets, under MC Settings.  Just make sure your sims are actually home.

A town reset is definitely not a last resort; in fact, many of us run one periodically just to catch any lingering issues that haven't made themselves known yet.  When I'm playing rotationally, I run one each time I switch households, typically every three sim-weeks, although that's a little more often than is necessary.  But there's no real harm in running them as often as you want, other than perhaps a bit of inconvenience.

At the crowded, overpopulated school in Sunset Valley a Yoshomo car ends up jammed into the front doors, front end poking out and slightly up and on an angle ... resetting just the lot caused everyone to get a tardy and some other negative things, so I've gone back to an earlier save and thought to reset the town before it happens. Will that work, or should I abandon the whole game ... ? Is it broken.

DivinylsFan​  If you reset the town while kids are at school, then of course they'll be reset to home and not be attending school at that moment.  NRaas StoryProgression should push them to go back, but it can take a couple sim-hours, depending on how many sims need to be pushed back to work or school.

For the overcrowding, you could put down a second school, and reassign some sims to go there (NRaas > MC > Sim > Intermediate > Career > Choose School).  Newly-aged-up sims should start choosing the other school at least some of the time too, especially if it's closer to where some of them live.  The SP Career add-on allows for private schools at various other rabbitholes, so you could for example have some sims attend art school at the theater, or something like that; I don't use the feature myself.

As for why the car is getting stuck on the lot, is this the default version of SV or a new one?  An edited map might have broken routing, but the original is pretty solid.  Still, you could replace this rabbithole with one from another world if you want.  You could also edit the lot if you notice a particular spot that's a problem.

This mod is also helpful:

https://modthesims.info/d/568897/additional-entry-and-exit-routing-slots-to-reduce-door-crowding-schools-university.html

Note that you'll need to widen the path around the back entrance/exit to make it usable, but that takes thirty seconds.  And you'll need to run another MC reset afterwards if you're not starting a new save.

As for MC resets in general, I always try to run them in the middle of the night, or before the workday starts, to avoid issues with sims leaving work/school/other activities.  If something is stuck in the middle of the day, you can reset only that lot, or only the object on the lot.  For example, in this case, you could click the ground of the school lot and select MC > Object Reset > [car name].  If that doesn't work, run a DebugEnabler reset on the car itself.

Ooh, aging up, that's an idea. Then they can overcrowd the career rabbit-holes. Ha! Yeah I'll try a reset at midnight. 

I tried doing a reset for the car, it didn't come up. Only a lot reset. I sensed that maybe the car was stuck to one of the sims waiting at the doors, possibly a worker, possibly Blair Wainwright. A dark blue Yoshomo. 

Anyway. I started back on an earlier save before the baby was born and enrolled my teen in boarding school a couple of days earlier than the other save, which was after the baby. 

Bah! Do saves ever go well in Sunset Valley? They always seem to stuff up for me. I can't save the household and start them again in SV because I've already married Emma Hatch into the family. 

DivinylsFan​  For what it's worth, I haven't abandoned a save in Sunset Valley for performance or corruption reasons since I switched away from playing on a 2010 Mac, running the macOS version with its 2 GB RAM limit.  That's not to say nothing has ever gone wrong, and I do abandon saves for other reasons, but I don't think the world is inherently unplayable for any length of time.  In fact, it's one of the most stable worlds overall.

What can be a problem is that it doesn't have accommodations for features from later packs, or that adding those features can clog up the town.  There's a reason that the newer worlds all have at least some combination rabbitholes—fewer overall means more space for other things.

There's also the fact that every world has a soft population limit, above which the game engine will start to drag on any system.  I don't know how many resident sims are in your world, and this limit is pretty high in SV from what I've heard, so this may not be relevant.  But letting SP go wild forever is not conducive to long-term saves no matter where you're playing.

I have discovered that the reset removes the memory for 'paint from memory'. So I went back to the earlier save again and got my sim to paint the 'paint from memory' first, during which she gained level 10 painting, so then I got her to start a second one, hoping it will be a masterpiece and worth more, and got her to stop midway and participate in the reset. The started memory-painting has remained and she is able to click on it and choose 'continue'. Haven't gone through it yet though. But at least I'll have the first one she did, of her son and Emma's wedding. The new couple had just tried for a baby with successful tinklebells before the reset, and I'm hoping that will remain, as a fully progressed pregnancy did in my first reset attempt. The teen who was enrolled in boarding school, in my first reset attempt, reverted back to being in regular school and the father had to enroll her in boarding school again. So this time I've waited until the reset and will enroll her now. The save I've gone back to this time was before she was enrolled in the first place. Nothing major had happened in that time before, except the baby being born, so its no big deal, because the baby had not grown up yet in the later save and its been months since I played it and didn't get particularly attached to it.

I'll give it a different name and preserve the later save on something and never play it. Like an immortal fantasy-pixel ...

Good to know that Sunset is solid and stable as you say. Pity about the missing accommodations. I'm guessing that would be dive spots? I would have thought though that all expansions have Sunset Valley in mind with getting added to. 

DivinylsFan​  For accommodations, I meant any rabbithole or venue that comes with an expansion pack or only applies when certain EP content is present.  Dive spots count, but so does the consignment store, the equestrian center, various clubs and performance centers, etc.

The point is that newer worlds were designed with the idea that many players would want to have all of this content in their game, owning more than just the EP associated with that world, therefore certain default rabbitholes could be combined to free up space.  So whether you own only Pets or all EPs, the school and stadium in Appaloosa Plains occupy only one lot, as do the hospital and science lab, as do the business/journalism building and the bistro, as do the grocery store and diner.  There are a consignment store and fire station that are of course only placed in AP if you also have Ambitions installed, just like in Sunset Valley (not the same builds either).  But if there were no combo rabbitholes, there might not be enough room downtown for everything players wanted to use.

On the other hand, nothing's stopping you from harvesting the combo rabbitholes from other worlds and placing them in SV or some other early world that lacks them.

I'm glad to hear you've worked out the other details.

I have Ambitions, but no Appaloosa Plains. What pack is that from? I don't see it as a separate world on The Store.

DivinylsFan​  Appaloosa Plains is from Pets.  I meant that if you have Ambitions installed as well, the game will place a special AP-themed consignment store, as an example of how the developers did build in some cross-pack compatibility and therefore some venues from other EPs get added automatically.

Ah, I wouldn't end up with Appaloosa, I don't fancy Pets. I've wondered about whether the egg and milk thing on The Store would work without it though. 

Do you think I will end up with complications if my household go on vacation to one of the WA locations while my teen sim is at boarding school? And what if its just a couple of them, while the elders and the baby stay at home?

Once, in a past Sunset Valley household, after they went to WA without the baby, when they came back the toddler was floating up in the sky, unharmed but stuck there, with an affected moodlet but I can't remember what. It was on a different computer. I heard something about needing Traveler, but I was reluctant because of not wanting to alter the original gameplay of WA, which I think Traveler does here and there, and then I was advised to also have Mover, but I have found that with Mover when arriving at a private house, possibly also a dorm, at University, a bunch of maid's or someone else's faces appear in the portrait area for a few seconds, making it weird, and creepy. And I heard there is some kind of bug that always ends up messing with WA travels anyway, needing the Traveler mod. 

This household has been to University without the first generation's baby (with a babysitter), multiple times, and they've also been to WA once it was a child and teenager, and they all went together, multiple times. There hasn't been a similar glitch like that old save with the floating toddler . But there is this thing with the school and boarding school ... I haven't played it through since going back to the older save yet, doing it now, but I thought I'd ask your opinion on the going WA while she's at boarding school. If she ends up going ... I'm about to find out in an hour or so.

And while we're here, which world was supposed to be for Ambitions? The automatic placement of the Ambitions lots in Sunset Valley are very sloppy, facing the wrong way and their paths aren't touching the road. So I wonder if they were made for SV or another world, and which.