I play vanilla with many many households in rotation and I never have had any issues except declining relationships. I want full control of all my sims, so I would notice if they would be doing something different or something would change when I'm not playing them. So, no changing jobs, money or romantic partners, thank god. They do walk around town while they would be supposed to work, but I think that's fine because it doesn't actually affect their jobs in any way.
I have noticed, though, that if I start a club gathering (with Get Together), not all of the club members always appear and I have assumed it's because they are at work (or supposed to be at least). So in those occasions the game actually registers that they have jobs at certain hours, which is kinda funny.