My bud that built the first lasting set of wheels for me let's me check the tension after the build. I do it by feel then take it in for the check. I've been right so far with 5 out of 6. He said the 6th was close but didn't matter, it would be ok. Being the way I am, I added more tension to ease my mind, re-check and good, no problems with the wheel.
You can feel a new wheel at the shop. flick it with a finger nail and set your build to match the feel and sound. Should put one in the ballpark after some experience. I like to check them to ease the brain!
He's an excellent mechanic and builder. I followed him around from city to city. He provides on the spot service and I tip him well when he does. But I don't need much anymore. Once I walked in with thrashed bearings in my tandem wheel. He dropped everything then rebuilt it on the spot, charged me $12!
How's that for service, I tipped him $20!