No idea how people are rotating 100's of sims??
But rotational play in ts4 is fenomenal. I like to bond with my families so I only rotate between 3 households. I'm not entirely sure what your question is but you can easily use the household manager to swap sims in and out of households. All of the ones I mark as my favorite do not progress (as far as I know. Maybe minor things?) so I don't worry about what they are doing when I'm not playing them. I prefer to have total control. So for example if I want sims from two different house holds of mine to go out, I swap sim 1 into sims 2 household and have them go out that way. When the outing is over and it's time to go home I swap them back.
All of my familes are max households. It's easy to manage but only because I use mccomand mod to slow down time and sims needs to my liking. It gives me freedom and time to do things I enjoy instead of fighting against the clock
