sellers, how often do you check your auctions

Constantly.
Buyers nowadays are in the habit of emailing about half an hour before the auction ends, so I make sure I'm available when one of my auctions is ending soon. Even if it isn't, I usually answer within a few minutes, unless I'm in class.
Which is why I can never understand why I only have 4.9 on my "communication" stars, my communication is a LOT better than most of the sellers even I've dealt with.
 
I probably check my auctions every hour. That way people dont have to wait to long to respond to ??. My computer stays on all days as well I just come back to it every so often!
 
On weekends and any day I'm not at work I'm checking Ebay and my email constantly throughout the day (when I'm home). If I'm at work it just has to wait until lunch or when I get home in the afternoon.