If somebody insists on doing a running clearance check for some reason, at least try to find one of the Snap-On GO/NOGO feeler gauges with a .002" step-up about 1/2" behind the tip of the feeler gauge blade, for instance .010"-.012" on the same blade. Those gauges were designed to simplify valve adjustments, as it's easy to tell when the adjustment is right.
Jerry