I usually check my cuttings once every 5-7 days (I guess my thread might indicate that). This year, it's mostly been checking on a friday, a saturday or a sunday, sometimes on a monday if I'm behind. When I know I have some stuff ready to pot, a lot of times I'll check all of them, so maybe I'm fibbing a bit and I actually check twice a week lately ;)
Chances are that nothing is going to change in less than 3-4 days at a time, so checking daily or multiple times per day is probably overkill and may actually cause more harm than good.
When I'm getting started in the first couple weeks, it's not uncommon for me to lift the lid and use it to fan the bin for 5-10 seconds to push fresh air in, then put it back on (cracked 1/2" or so at the corners). I don't usually bother with checking roots till 2-3 weeks in, and I'll check once or twice a week.
(I sure hope more people come in and give their subjective opinion, just so I'm not one of the only two voices you hear from)