I use bottom entrances, and I find I use the notches hardly ever. I don't use inner covers on all my hives, because some have migratory covers, and I also have one inner cover that doesn't have a notch (it's identical to the other one I bought at the same time, so I think the notch just got missed at the factory), and I've never been like "dang, this is the one without the notch, now I can't do this or that thing". I do use moisture quilts over the winter for humidity control though, which takes care of my ventilation during that season. If I didn't have a moisture quilt, I'd definitely want the notch then.