Yeah, I was eyeballing this one for a while.
I have cut with lots of guys that don't gauge the depth gauges.
Mostly they are Certified Utility Arborists (CUA) They were taught to keep the teeth even and that's how they teach.
Friend of mine, Tom, he's a BC Faller/Supervisor. Cut a lot of Seismic and pine beetle work with him in the interior.
He never used a gauge. His felling cuts are ace.
Starting to get the fever to get back cutting again soon. I had to tuck-tail back up to London for work after the first lock-down at the end of June, 2020. Residential construction has been good since. People were bored and couldn't go on holidays so they spent it on their houses.