I have gone into three different hives this year and found only a queen cell or two and no other brood except a few drone brood about to emerge. That seems odd, as to me it would seem there should be at least some worker brood around in the colony somewhere. I will note something here.
Two of them were requeening and I was expecting a laying queen just to find one lonely capped queen cell. If there was a new queen that started laying and something happened to her I understand that but absolutely no brood seems strange.
16 days for queen
21 days for worker