a toughy...well it depends. i chose less than an hour. i mostly draw in school because well it's boring. i draw a lot more sketches at school than the total deviations and scraps i have put together. when i'm home, i barely draw. i probably draw for 5 minutes a week.
I try to draw something at least every day. Mostly pencil but sometimes it's on the computer.. Computer takes longer though since it's mouse driven and I always feel obligated to finish. Sometimes it's less than an hour, and then other times it can take up to 6 hours..so yeah.