A 3/4 inch hole in any brood box is not too much.
It may be too much if you add it in the fall. But if your hives are configured with a hole in the brood box and the bees are allowed to arrange, fill, and manipulate openings as they see fit, then they will do just fine.
I have upper holes in almost all my second brood boxes. These allow ventilation with a full draft through the entire hive. An upper entrance (not to be confused with a top entrance) will still allow a trapped area of heat, that benefits early spring brood rearing, and allows the bees to cluster draft free at the top of the hive when they need too.
For me, much of the top entrance advice (which goes against what bees favor in site selection) is hysteria and hype brought about by beekeepers feeding syrup in the fall and causing this unnatural moisture condition to begin with.
In nature, bees prefer a lower entrance. And in situations where a tree may offer multiple entrances which you will see many times, the bees build comb in various configurations (not straight) that inhibit drafts, and allow the bees to control moisture in ways that a modern hive does not allow.