Head's Up Hold'em has a nash equilibrium. Therefore there is at least one mixed strategy (I do X with probability P in Y situation) which cannot be negative expected value to any other strategy. In this sense, there is an optimal strategy. It doesn't mean that it is the maximum expected value against a particular opponent, but no opponent can win by playing (which is largely the goal of a casino).
Opponent modeling is purely advantageous, but not necessary
Opponent modeling is purely advantageous, but not necessary