I generally make a set of 3 target arrows for each bow I make and tune them to that bow. 3 more if I plan on hunting with the bow. I make them all the draw length of the bow and no longer, that way I can never overdraw the bow when I use the arrows that were built specifically for that bow. I have some bows with a draw length of 28", and some bows that only draw 25". But, I think I am different in this regard, as most people just have certain spines that they use for a number of bows.