I usually restart when a new idea for a new household strikes. I rarely replay my sims because I have a tendency of doing the same things over for them. I did restart my Westbrook legacy over. It wasn't for a different idea, just because I failed to take screenshots of the triplets in the fourth generation when they were toddlers. It made me lose interest because to that point, I had screenshots of every sim from all lifestages in every generation. I think sometimes I'm too absent-minded to be this much of a perfectionist control freak.