I like the idea of bees opening and closing upper ventilation holes with propolis as needed.
I imagine the number of holes in the box would depend on your climate
more holes in hot or humid climate than cold or dry climates.

How large a hole can a bee propolize closed?
Would you drill the holes on all sides of a hive box
so bees could take advantage of predominant winds
by opening and closing holes to windward or lee side of hive?

Since bees would propolize holes open or closed
when ventilation is not needed or not needed
would it be a good idea to have these "vent" holes available in all boxes
so the bees could open and close holes from the bottom-most to the top-most box?

Would it be better to have a horizontal row of holes all at the top of the box,
or more than one horizontal row with one in the middle and/or bottom as well?
Or vertical holes going up and down near the corners to avoid any draft on central brood section?

How would the holes and their location affect the structural integrity of the box.

Doug from Bandon, OR