The good thing about doing your own servings is you can make 'em any way you want. If you're one of those guys who never hits your arm with the string, even by accident, then all the serving you really need is just a few inches - enough to protect the string from your nock and release with enough extra to allow for tuning adjustments. The long serving is there simply to protect the string from abrasion due to contact with your arm/armguard/sleeve.