Yah I think it is standard, and I would use that sizing with all my bluffs as well.

But once i DO choose that size, I just wouldn't be contemplating folding very often, that's all.

I mean what hands really make sense for villain to be SHOVING outright here, that don't shove preflop? He'll probably jam AK pre. He MIGHT play AQ this way, and it could make sense for him to just shove AQ. AJ? AJ might call sometimes, since it loses to AQ/AK, but I suppose it could shove as well. I doubt AT (if he has that) is shoving.

KQhh? QJhh? JThh? Any other flush draw might also be jamming here.

By my calculations we need about 37.5% or so equity to b/c here. I think this is one of those important spots where equity does not tell the whole story. This is the approximate equity we have (assuming villain is only shoving AQs/AJs - to discount some times where he might call flop instead):

Ad9c 35.16%
AxQx,Axjx,KhQh,JhQh,JhTh 64.84%

Looking at this we could conclude that we should not call, since we don't have 37.5% equity vs his range.

What about if we bet 30bb on the flop? Suddenly if we bet 30bb on the flop we only need 30% equity to call. So now this is a clear b/c.

Does this intuitively make sense? If we bet bigger, and represent a strong hand the math tells us to call, but if we bet smaller and represent a weak hand, the math tells us to fold.

It's important to think about all of your sizing options and what they might do to villains range. This is a spot where hero could easily bet 30-35bb on the flop and say "shrug oh well he shoved, I'm priced into calling". But it's clearly better to bet 15bb here, induce a shove from villain and call (when the math says not to, within reason ofcourse) vs a range that is likely weaker than in the former situation.