Tap drill charts are for when you're fixing your lawnmower or BBQ.
For real machining you get out your Machinery's Handbook.
Though somewhat facetious, charts are starting points, and each job has unique requirements. Most of the time a 65% thread is just fine. Sometimes if you have a nasty material you may have to drill a bigger hole that results in a 65%, simply because of tapping issues. Much more than 80-85% thread isn't buying you much anyway, since you're well into diminishing returns on strength.