I'm only a newbie, but everywhere I read about requeening, experienced
beekeepers recommend requeening during a honey flow so that the older, meaner
foraging bees that might be more antagonized by a new queen will be busy
foraging instead of lurking around the hive.
I've also heard the thing about the strips, but I think it's the lesser of 2
evils. Get the queens in the hive during a honey flow, if possible.
John