The further an airfoil is from being symmetrical, the better chance that it will benefit from differential as a rule of thumb.

Semi-symmetrical wings benefit from a little (maybe 1/2" up and 3/8" down). Flat bottom wings can use more (1/2" up, 1/8" down).

But to get it right you have to test fly/adjust, test fly/adjust until you like the way it flies.