[stagpanther]

I have gauges for all my AR builds, but have never had one that didn't pass (bolt gun builds it's virtually impossible to assemble one without good gauges). Far more likely IMO something else is going to indirectly cause a headspace issue over time. Things like failure to complete lock-up of bolt lugs to extension, barrel extension slightly out of clock, BCG wear and misalignment to upper's bore. So it becomes a question of how often do you check your headspace? Here I plead guilty, I often "set it and forget it" until the gun starts showing issues.

There is also the question of who's gauges you use--they are not all necessarily the same in tolerances. I generally stick with PTG or Manson. I once did a build using a barrel that came with gages--and one of the gages itself was out of compliance.