I don't really understand your question
the area of open space can be measured in sq in
example, ( I'm really bad at math fo-reel, so I hope I have this right)
if distance between wand lips is 1/4" and wand is 12" wide, that's 3 sq inch of opening
I don't have a
glide, and any wands I have would be buried in the pole barn somewhere, so I can't measure.
But don't think the opening on a slot glide is all that different (smaller) than the unglided wand lip opening .
so they should be pretty much the same in your "feel" test
no clue how to calculate hole glide sq in
the only thing I know about Pi, is that I like peach pie the best
..L.T.A.