If you already have the gauges you might as well use them. The facial features you save may be your own or fellow shooter's. Unless you're re-barreling bolt-action rifles for hyper-accuracy, the no-go can be dispensed with, but it's desirable to have a go and a field. There are a lot of old myths about certain rifles said to be indifferent to bolt-swapping, K98 Mausers, 03-03A3 Springfields, M1 Garands, SKS's, AK's, AR's. It's true as a matter of design, but the one you bring home or assemble might be the one that proves the exception. This was discovered with the Garand and eventually the production of new rifles and spare parts at SA enabled rebuild armorers to be supplied with slightly longer and shorter bolts from earlier and later revisions. I.e., the one that came in a CMP M1 might not be "correct" per the receiver's year and month but it was a good fit for the USGI armorer who installed it. And we've seen plenty of arm-wrestling here with headspace issues that arise in commercial M14 clones depending on the receiver-barrel combination. Might as well get headspace right if you have the tools, or get it validated by somebody who does.