Roamus, you're thinking about a lot of things here (good) but you're focusing on the wrong stuff (bad).You need to ask yourself these types of questions while in a match.  Then the next match, ask them again.  During your third match vs a different opponent, re ask these questions to yourself yet again.  Why?  It's going to be a different (even if ever so slightly) answer for each player that you play, and sometimes quite a drastic difference.  Flatting AJ preflop may be easily the best play against one opponent, and 3betting it for value may be easily the best for the next opponent.  If you're 3betting AJ and folding to a shove, it's likely that you didn't think about your 3betting range prior to the 3bet, or more specifically how your opponent would react to 3bets and what that should do to your range.Now, there are some spots where you could 3bet and fold AJ, namely against a very loose player (calls your 3bets with a ton of hands) that does not often 4 bet you (tight and strong 4bet range would be an example).  Against that player, it makes sense to do this with not only AJ, but also with KQ type hands.  But those opponents aren't quite all that common, and you'd still call a 4bet shove if stacks dictated such (pot odds improving with you putting in more chips preflop with your 3bet).Otherwise, if a player has a tight 4 bet range, ask yourself what should you plan to accomplish with your 3bet range?  Do they call 3 bets wide?  No?  They are tight?  Well then you want to tighten up your value hands in your 3bet range so that you can call a shove with them.  This might mean 99+, AQ+, which is fairly tight.  But he's folding a lot to 3bets, so you need to mix in some other hands that you're happy to get folds from.  What's the weakest hand you call his PFR with?  Q7s?  So 3bet Q6s.  Q5s.  Q4s.  Hands that are just outside your calling range, that you'd otherwise fold anyways.  In the event that you are called with some suited connector that just wants to see a flop or a slowplayed hand, you'll probably have a bit more equity than if you 3bet 43s type hands here (though those can be fine, you just ideally want to be deeper where they play a bit better with a much better risk-reward ratio, but it is a 3bet pot, so risk-reward being good on those hands is going to require a fairly deep stack size, deeper than a regular husng will start at).  And if your opponent 4bets you, it's pretty easy to fold Q4s, much more easy than AJ.Oh, and that AJ that you weren't sure to 3bet or what vs this guy?  Now you can safely call with it preflop and your calling range just went up in strength.  Your 3bet range also is now exploiting his tighter play vs 3bets (he folds too often) because you've added weaker hands in there for fold equity, all while not even taking out a single PF calling hand for you to play OOP (you've actually added at least AJ, and maybe some other hands you previously 3bet but were just slightly too weak to do so vs this player).