I think many look at the "professional" video and standard classroom taught procedures, and assume that you must have a certain busting at the seem number of bees. Which is not the case. Maybe if you a commercial guy grafting 72 cells. But for smaller amounts, it is not needed.
I use 5 over 5 nucs, and some of the best queen cells I ever got was from a huge swarm that I pulled the queen out of after 24 hours. Yes, I use the stringest colonies I can find. But I also know for a graft of 32 or 16 (That is what my bars hold - 16 per row) you can get great queens with far less than what many claim you need.