Lets take a hand like J 2s. 30/60 lvl, villain opens to 120, you are sitting at 1200 chips. You 3b to 300. So you are risking 240 to win 180- you need the 3b to work about 57 percent of the time to profit.
Now lets say if villain folds to your non all in 3b 66 percent of the time(lets say he folds to a 3b shove also 66 percent) , would you rather just always 3b bluff/fold rather than 3b/shove? What are the circumstances where 3b/fold becomes better than 3b/shove and vice versa?

With a hand like J2s 3b folding is much better if villain is usually responding by 4 betting or folding. If villain flats a lot the expectation of 3 betting a hand like this decreases and instead you should 3bet fold a lot of value hands like JTs, Qts, etc. Also a 3 bet shove needs to work more often so you would need a fold more than 86% of the time here for it to be immediately profitable with any two cards. It is better to shove hands that have better equity versus his calling range too so if villain is opening wide and not flatting my shoves super wide I much prefer a 3 bet shove with 56s or 76s.

Additionally, its very unlikely villain has a fold to 3 bet that is the same for both non-all in 3 bets and all in 3 bets.