I check them every couple of days and put some more green stuff or carrot in for moisture. I fussed over them quite a lot at the start but just leave them to get on with it. They're in OH's workshop on top of a plan chest. I suspect the slowish development is because it's usually only about 17 degrees in there, unless he puts the heating on. I found every stage took longer than the info said. Probably the most time consuming thing is picking the pupae out of the mealworms which I did at least once a day, and the same with the beetles, but at that stage the box (ice cream carton) was in the kitchen so I just lifted them into another container when I noticed them.
Later today I'm going to amalagamate the two lts of young worms, take the beetles out and empty the bran they've been in into the tray I will free up with some fresh bran. Then I'll put the remaining beetles back in the plastic crated with fresh bran, the bits of egg carton and some greenery. I'm going to take one of the cartons of adult mealworms out of the fridge and let some of them pupate to provide another batch.
It only takes me a few minutes but some of the info on the internet makes it very time consuming - not necessary in my view. I don't bother to shake the frass out from the adult worms - it sinks to the bottom anyway, I just top up with some fresh bran. Then maybe once a month I take all the worms out and replace the bran completely. If you do it when the worms are newly hatched you risk losing eggs.