Just setting it to 6A was never the truly correct way to do it anyway, it's just a short cut, since the correct (and much more complicated and time consuming - i.e. tedious - method,) happened to end up around 6A most of the time, so people started just going for that directly. At some point in advancing timing, you'll see less and less gain of kv yet an increased rise of current drawn (means also increase of temps). I doubt you could get any two people to agree on what point the exact sweet spot is on relation to those two curves, it's just "when the amperage gets too high compared to the increase of kv"... sooo much easier to just straight go for 6A, right?