Thinking more about it, the shape of the solution space is sufficiently different for hair vs faces that any given combination of {optimization function, hyperp

Thinking more about it, the shape of the solution space is sufficiently different for hair vs faces that any given combination of {optimization function, hyperparameters, training data} is unlikely to optimize for both. You probably need some other sort of special tuning, like a spatially local adaptive gradient for regions of hair.