I just finished my first rotation on my current save and saw that I have played 42 households! It got me wondering how many households other people play (per saved game).
I think my current plan will put me at about 28 eventually, but I just hit 18 and it will be months before that goes up because I'm waiting for the spares to grow up and it takes a while for anyone to age when you're playing 18 households with aging on only for the active one. So at this point I haven't played more than 20 households at a time in Sims 4 yet, but I've been in the teens for at least a year.