I am experimenting with a 3 or 4 hole method. This has a series of 3 or 4 holes lined vertically at the end of the hive. With a 3/8" hole at the top to allow for ventilation and easy for colonies that need an easier entrance to defend. It is also always the open hole at all times, allowing the bees an exit/entrance without worry of being blocked in by debris accumulated over time, especially winter.
second from top is a 1/2" hole ( in a 3 hole situation, this one is not included, going directly to the next hole down)
followed next down by a 3/4" hole.
At the very bottom is a 1" hole which allows more traffic in peak times and easier "housekeeping" practices by the bees.
During good weather, all three or four holes are open and traffic is booming. If robbing should occur or other threat, the two or three bottom holes can easily be covered leaving the easily defended 3/8" hole at the top.
I have two hives working with this entrance type so far and I haven't noticed any issues out of the ordinary thus far. (coincidentally, these are the only two hives I have going right now into winter, as my yard is WAY too small to contain any more. when spring comes, I am crossing my fingers the new, much much bigger beeyard will be ready and able to be used.)
Big Bear