Twice a day for me.1 when I wake up with a hard on, and 1 before bed. sometimes 3-4 at the weekends when I have more time to myself.
At least once per day. For certain I masturbate to relax and get a good nights sleep. It's also a good way to start out the new day, either in bed being lazy still or in the shower with all that hot water beating on my back.