When I run out of room in the hallway/roof/lawn.
When a sim is born, ages up or their style changes.
When I add a pet to the household and need to make room for their stuff.
When there's a fire, repossession, theft or other disaster and I have to replace things anyway.
When a partner/spouse moves in and I think they are the type to redecorate to their own tastes (and assuming the original owner is the type to let them). This could end up with no changes, a blend of both sims' aesthetics or a complete spousal takeover.
When I'm not actually playing those sims, but are playing as an interior designer via another household in rotation.
