Sonny said:
Bet the table max when you have the advantage. Do not bet when you are at a disadvantage. That will give you the highest EV. That does not take into account heat, risk, bankroll growth or any other factors.
Technically, any flat bet whenever you have the advantage will have the same EV (whether it's table min or table max) because EV is normalized to the amount bet. You can actually increase your EV by ramping your bets, but it will lower your win rate.
Theoretically, your highest EV will come from waiting until a +infinity true count, and then putting down table max. But your win rate will approach zero.
Edit: the highest possible Hi-Lo true count, I believe, should be +52. This would correspond to the probability that not a single ten or ace gets played until the very end, so you end up with a RC of +5*Decks with (5*Decks)/52 decks remaining.
Edit #2: At a true count of +52, your edge is about +9.4 (you can expect to nonuple your money on average) assuming infinite resplits. Basic strategy is to hold on all blackjacks and split any pairs. Always take insurance.