Friendship Is No Longer About Killing Time
In Your Twenties: You don't have a lot of responsibilities outside of work or school, (and, let's be honest, those responsibilities aren't as intense as they get to be later). Accordingly, when you have time off, you spend it with friends just hanging out.

In Your Thirties: Adulting has gotten real. Not only have your career responsibilities ramped up, but you may also be married and even have children. As such, time with friends fits into more defined slots with much less lingering.