I always use my gauges vertically. I have both the Manson style mounted to a wall and also have the British style wall thickness gauge, the type you’d find in most British & continental gunmakers shops. I much prefer the latter. My mitutoyo dial indicator is as good as it gets, and the readings when using that very rigid British style gauge are dead accurate and repeatable. If the gauge your using works correctly and you’re getting accurate readings, it doesn’t matter what type it is. I much prefer the British style gauge over the Manson though, but that’s just me.