How Does Rotational Play Affect Progress?

I play several legacy families in my main save, in a loose rotation that doesn't plan out things by strict week, and it works really well for me. I play vanilla so I don't have mods getting sims into mischief I didn't anticipate. (Also, I agree, it's best to leave aging off if you like having NPC friends or neighbors around for a longer period of time.)

I have all my legacy families get married and have kids at about the same time, so the kids can age up and go to school together. I play each family until the kid ages up to a toddler or child or teen, and rotate to the other families as needed/as I feel like to get their kids to the same age.

In terms of the more unique situations of pregnancy and university, I don't rotate for that time. It works best for me to have only one pregnant sim at a time, so I can focus on her and getting the baby to toddler stage. I also play only one set of sims at university at a time and don't leave them for the duration; they usually live in the dorms or in a house as a group, so they can all do their homework and hang out together.