I started with foundationless frames so I go in a little more often than I want to check and straighten comb. Right now it's every other week. The brood box is fully drawn, so I don't have a reason to go in there.
Last inspection I did check the brood and found one of the frames with a lot of capped drone brood. The frames on either side was worker brood. I thought it was late in the season for drones, but if they feel they need them, so be it.