@jongordon84 I was kind of thinking same thing, but I thought about it some more and realized there could be some default positional matchups that it might be ok, as well as some exploitative spots with specific reads on a villain that it might be warranted. However, I also kind of feel that, if you feel like you are going to have to 3b AK and make a tough decision on whether to 5b jam or fold, that maybe it would just be better to flat the AK and take it to the streets. If you are 3b folding AK then you are basically using it as a 3bet bluff, which doesn't make a whole lot of sense to me, but maybe someone else has some insight as to where that make sense.
I mean if you had HUD stats on a villain and could see that they are only ever 4betting AA and KK and have virtually no 4bet bluffs, then 3betting and folding would be ok, but again in a spot like that I think I would just flat it. I guess if they open a lot and call 3bets a lot then it is still a value 3bet and you are doing really well when they call your 3bet, but you are just in bad shape any time they 4b. I think it is probably a pretty rare case though.
For me I tend not to 3b AK when I am MP or CO and facing a UT open as their 4bets tend to just always be AA and KK, beyond that I agree I think 3b/5b stack off is pretty standard