If you know you are just going to build it once, measure twice and go for it. If you think you may build it again, make a template! It will save you time and get perfect results.
Even if you only think you are going to make one of a project, I always try to make a template if I think it may help.
-- CHRIS, Charlottetown PEI Canada. Anytime you can repurpose, reuse, or recycle, everyone wins!