I find value in both.
When I'm in a social league, I try to experiment with different lines/angles to the pocket, different ball speeds, different releases, etc. There's also the added benefit of the chaos around me. By that I mean that I can work on my concentration and focus by attempting to block out the non-existent lane courtesy, the boorishly loud drunks, the "I think I'm good so I pound ball returns when I leave a half ten pin" doofuses, and the usually too-loud music that they play over the speakers during league.
In turn, that lets me hone certain skills that I wouldn't otherwise get in the more "sterile" surroundings of the better leagues that I bowl in. So, while I'm bowling in the better leagues, hopefully my game is sharp.
If I ever saw an amputee being hanged, I'd just yell out letters. --DM