I heard that channel boards can have problems with screws loosening and the bingings sliding. how often should I check them for loosenes?

Initially upon launching the channel, Burton used to have a few very minor problems with loosening, but the new hardware (and rubber washers) have fixed most issues. None-the-less I check my every few times I go out. Honestly, if you put your binders on the board when everything is dry (so no moisture is underneath), you should not really have to worry about tightening much at all.