Well I lacked any measuring instruments at the time, but that's my educated guess of the dimensions. Optical centering means the print is centered left to right and mounted such that the center of the print is slightly above the vertical center line of the mount/frame. The amount of adjustment can be determined by a graphical construction as shown at the link i posted back on page 1. The adjustment is obviously proportional in some fashion to the various dimensions. My feelings about the top and sides equal is a question of the degree of difference in the bottom. That method would likely bother me much less if the lower part were maybe 1.25 or so times the top and sides (or less) versus the 2 x of the mount I disliked. The woman had quite a wide assortment of frames and mounting styles, so it was a chance to see a bunch of ideas in play.
As far as frame size vs print size, some folks like a wide margin around a print to provide its own space, isolated from the frame and surrounding pieces - a gallery within a gallery -- sort of.
So, opinions are like noses -- almost everybody has one ...
Years ago I heard of a show where one of the requirements was that all work had to be in 16x20 frames.
Edit: There is a magic condition where optical centering can reduce to top and sides equal. The interactive script at that link above actually warns of that condition and suggests regular centering, especially if the top gets smaller than the sides. Who knew it could all be so much fun!