i know city living was left out as hidden cause it would take up nearly the week on a 7 day calendar then the player wouldn't be able to add their own events.
i mostly use 14 day calendar and the preset festivals & holidays appear the same every time. As i started getting more packs i had to write them down in a pad, so i would know which days not to have special events if i new i wanted my sim to go to festivals
Humor & hijinks Day 2 per season
Romance day 7 per season
flea market day 8 per season
geekcon day 10 per season
Love day only spring day 13; Spice festival day 13 per season - as you can see love day is a holiday on calendar spice festival is hidden so you still can plan an event on the 13th
Harvest fest only fall day 12
Winterfest only winter day 11
New years only winter day 14
I haven't written down a 28 day calendar cause i only played that a few times but i'm guessing humor would appear day 2 & day 16, as well as the others appearing twice per season
Discover uni- i'm guessing again its left out cause only your college student can see the schedule all the time when they join a college organization,since technically its only for the student and not all household, thus if your student isn't in the club,then that's when the invite aslo appears in the corner so u have the option to attend.
Although don lothario keeps showing up as a guest partier in my game all the time
island living - in my game the festivals happen all the time in 2 different locations if you stay in those active areas long enough a festival will appear, so they feel there's no reason to waste a calendar event slot for something that appears often.
get together - are u talking about the events, bear night, cheapskate night, alien night,cause again like island living they appear when u visit the bars,so no reason to take an event slot