if the entrance gets to be too congested as the hive grows in number, could that induce the bees to swarm ? i kept my entrance a bit on the small side thinking i don't want to invite mice inside while the bees are still few in number.
As long as there isn't a traffic jam I'd leave it small. Once there is a traffic jam, I'd enlarge it...
Look at how many huge cut outs people do at homes and how small most of the holes that the bees use. I left my entrance reducers in this year, but I have screen bottoms for air.