i dont think you can 4b/call at NL4 unless u know he stacks off with AQ and some random AX or smaller PPs.
Although the sample size is too small, but from three cases he has folded to a 4bet only once when in BB, and combined with his high 3bet % I would not be too surprised to see at least the range that you just mentioned. Of course, I am not too sure as those 2 other cases when he did not fold might just as well have been mosnters.
But –
For example board is A72r, I will c/c once because I expect him to bluff once and then give up. Board is 722A. I will c/c twice because I think he will 2barrel bluff.
As much as these examples and the explanation make sense, these are obviously not the only postflop scenarios. True, a call on a dry A-high flop is not the worst and toughest spot most of the time, however, the second example you gave already gives us some problems – I would assume that there are quite a lot of Ax hands in his range (because these are great to 3bet with IP for the blocker effect) so I would have to think actually before calling that bet on the turn (depending on his bet-size it might turn out to be a rather difficult decision), our opponent would (should) also know that once we call on the flop we basically have a pocket pair and he might be willing to push AI on the river to force us out of the pot (which should work(!)). As much as I might be exaggerating our opponent's competence, there are many other difficult scenarios –
consider these boards – 2TJs, 4Q6s Ts, 246ss aso. with multiple combinations of other ugly flops + ugly turn and river cards. The thing is – I strongly disagree that postflop play in this spot is easy.
It would be easy if I had payed close attention to every single step my opponent has made and if I indeed had a distinct feeling for his play and betting frequencies. Would you really suggest me to call preflop without me knowing my opponent well enough to assess his range once he makes that pot-size second barrel, for example, on a K26r 7 board? Even on a 633 A board?
Given this explanation, would it not seem that a 4bet/call (we get some fold equity even) is not only the safest and easiest approach but also the most sensible one?