Interesting you posted this because I was just thinking this very same thing when I went to a Master swim tonight -- how many are joiners versus solo.

I signed up because it's easier to know a pool's available in the evening (my rec center caters to swim teams/clubs) but I dislike being pigeonholed into a timeframe, so I do most of my training on my own. And then I have this weirdness set in if I don't show for every workout -- even though I know I've been training on my own.

My work is somewhat flexible so I can do a lot of switcheroos on workouts.

Oh, and the other thing is I'm turtle slow, so when the tri club meets for workouts, I just assume I'll be left behind <sigh> -- though I might screw up the nerve to join them this year.