I read on here a week or 2 ago about folk just lifting boxes and having a look at the bottom of frames for queen cells rather than doing proper inspections. I personally think that is really bad advice and lazy beekeeping. Bees don't listen to this stuff and do what they want, when they want to. This is a picture I took on an inspection a couple of years ago. I had fully inspected a double brood colony and not found any queen cells. As I put the supers back on I always pull the centre 4 frames just to check as bees move eggs around the colony and above the queen excluder and I found this. I usually find this at least once a season. Don't get caught out, this queen could emerge and the bees remove the cell the next day and you would never know what just happened.