General question about ND Filters: when do I need a square filter ?

General question about ND Filters: when do I need a square filter ?I know that with wide angle lenses, say, 10-24mm, it's useful to have a big square filter as a ND Filter, to avoid vignetting etc. I experienced this, especially at f11 or more. Is it the same with 35mm, 50mm, 90mm lenses, or would a round filter, put on the lens, work in these situations ?I am actually looking for a 43mm adaptive ring for my lens, but can't find any, therefore i could get a 43mm filter instead (even though I already have the square filter) via /r/photography https://ift.tt/37nF2V2