[Johannes Guerreiro]

Put all your strokes effects and masks in a solid layer above.

Switch all paint styles in the stroke effect to “on original image” except the first – it should be “on transparent”.

Then just set the solid layer to an alpha tracking matte of Your original layer.

Now You can control every stroke effect for every mask separately.

(Btw. sometimes You can change the single mask timing with one stroke effect for all masks with the simple length of the masks… but that’s a bit dirty with possible problems.)