I personally have dropped back to just 15 cells at a time, wait a day the I can add 15 more to the same hive, this is a queen right hive I am talking about, I learn this from Dwight Porter (Redtractor1) a member on this site. he got it from the Russian Queen Breeders Association, makes good quality queens at a almost no bad results. you can over load a cell builder easy and have some not so good queens but some still have good luck with it, it all come's down to quality instead of quantity for me. I would rather sale a quality queen by percentage than by numbers because I want people to get what they pay for. it cant happen getting a bad queen but odds will be in my favor by far. I am not selling any this year because I am building up hive counts and going to sent just a few test queens to friend in different location to test for me. my year is booked and I havent even told the one's I am going to send them to yet but will soon by PM ;) . also have a number queens sold here locally for friends. and I use the plastic push in cell cups from W. Kelley