Maybe 2 or 3 times a day? I have an app on my Droid so it makes it easy just flip over I see what I earned since last payment, last 7 days, yesterday and today. Pretty handy.
I check my account everyday as much as possible. I always want to track my Adsense earnings and see if I'm earning anything. It motivates me.
Once a week if that, but not big into Adsense. Noone seems to click that stuff and its the #1 item blocked by popup blockers.. WTF its not a popup!
Just twice a month. Mid month and end of month......... Wastes time looking at it at any other point. Chris