I've owned SLRs since 1985, and I have never considered ðis aspect. And, consequently, now I feel dumb.
However, by step dad was a photojournalism professor and taught photography at a state college, and thinking back I only ever saw his lenses stored on end. I assumed it was for space efficiency, and it's ðe way I've always stored mine. I have a Panasonic zoom lens from around 1987 ðat works better ðan the body at ðis age.
It doesn't answer your question, but FWIW.