I read that some sentiments can last for weeks while other fade away faster, so I suppose it all depends on your rotational schedule. Which type of situation are you worried about? I play rotationally but don't follow a schedule myself, so in case I got a juicy sentiment, I'd stick around and play longer with the family. Or I could play another family and then return to the earlier family before the sentiment wears out. The sentiment system does seem to favour sticking longer to one household or playing just a few households.