I got one of the cheap Amazon tension meters a year or so ago, and I find it helpful. I am usually just doing used wheels. I like it for getting things a bit more consistent. Checking older wheels I have done by plucking, the meter shows the range of the spokes was off perhaps 3-5 units on the gauge. Using the gauge now, I can get around 2-3 units variation on these older wheels. I guess it makes me feel good. I don’t use it for absolute values, just an aid for consistency. Only once did I build wheels with NOS rims. That was pleasant.