I'll agree that it can be important as outlined by zxcvbob--but only if one is out there working at the ragged edge.
Some years ago I was enamored with 9mm, and I tried all sorts of 356 / 357 bullets, from standard nine offerings on up to 158-gr. stuff. That was pretty self-limiting, however--the longer lengths precluded satisfactory seating; the case would bulge--and if it didn't, the volume was too small to put in an overpressure charge.
Cast bullet molds are now fairly stabilized in terms of design, and semi-auto bullets (typically) have no cannelure. Bullet manufacturers, of course, do provide the dimensions, including LOA (if not charted somewhere, they will if you ask).
So, gather the information for the specific bullet you want, probably by calling the manufacturer.
Jim H.