I’m not a coach, so I don’t ever advise others on how to measure them, and I’ve never trained an advanced lifter, so I definitely wouldn’t advise them.
For myself, I measure results using a combination of the mirror, how my clothes/weight belt fits, and my performance in the gym.
If they’re getting the results they want from it: it’s doing the job.
Whenever I run 6 weeks of BBB Beefcake, I get the results I want from it. I did a recent write-up of it here