"AWWW, WELL AIN'T DAT CUTE. BUT IT'S WRONG."
No seriously, quick sketches that only take 5-10 minutes is the best way to learn how the human figure works in movement and the proportions of it. For quick sketches, you SHOULDN'T be spending more than that on them anyway. Go to a site like Posemaniacs or something, and try drawing a bunch of figures in 5 minutes or less. It's not about detail or accuracy, it's about how you can learn the body and how it moves.
Okay but seriously, before Circ kills us all for talking about this, I've got an Art Critique thread on onehitcombo.net if you want to swing by and discuss this stuff. Probably a better place for it than the Blazblue fanart thread.