This is a question that has been circling my mind for a while.
I have heard some people say that playing blitz creates bad habits of not calculating enough, and playing more by "instinct".
I have also heard people say, and I agree, that what's more helpful is to get lots of practice, play lots of games against good opponents.
So, when you get to a club for an afternoon of chess, is it better to find an opponent and play one game with slow time controls, or play 10 blitz games instead?
When I say better, I mean in the educational sense. Let's say you have a set opponent for the afternoon. He's good at blitz and standard chess, and a bit more skilled than you. What would provide the better learning experience, a single game with slow (or no) time controls, or play 10 blitz games against that same opponent?