So then would you buy several sets of mandrels at different sizes for different woods so you can service them? Then keep a standard that all of your cues of that wood use that specific joint size?
All you need is one set that is undersized. No 2 pieces of maple tone out at the same size. There could be a .001 or .002 or even .003 difference. Ever wonder why one cue plays like a monster and another made with the same woods and the same size only plays so-so.
Most people looking to buy a cue do not have a clue. They come in and look at your cues and see one that they like and buy. The players come in and want to hit with every cue until they find the one that has that feel. They could care less on what they look like. I strive to make all my cues hit like a monster.