Actually, if I am reading the listing right, the Snap-On tool is not like a Click-Adjust. The Snap-On still has you using the traditional feeler gauge, it's function is to combine the work of the screwdriver and wrench into one unit that preserves the original setting until it is adjusted and then preserves that setting whilst the lock nut is tightened.
I just note what o'clock is the correct setting, then back off a bit before tightening estimating how much the adjustment screw will move (not much) as the lock nut gets its final tug. If I end up at the spot noted, all is well. Of course all valves get re-checked after adjustment whatever method you use.