I have one big save since the beginning of Sims 4. There are over 600 sims, every one was edited one way or another. I play rotationally about 40 households. Which I play it depends on mood or on packs I want to play. For example, when I want to play with cows and chickens I choose a family which lives in Henford and have enough space to buy a coop and shed. I also come back to "old" families when I want to check new features or new packs. Although I have now created (in that save) new household with infant, purpousely for new update and new pack that I will play. Of course Sims I play have many friends, I visit other households on purpose, so I have very complicated connections between them :) I play with aging off.