Some cats do much better when they have other animals or cat friends to socialize with. It depends on a number of factors, and much like human, not every cat is the same.

The amount of desired human attention sought from cats in our household has has decreased as the number of cats in the has increased. That's not to say they don't still want our attention, or that we don't give it to them. Having friends to keep busy seems to make the days go by easier.