Both Martin and Omar are exactly right that it depends on whether the transition needs to be sharp or smooth. If I don’t smooth the mask, that means I want a sharper transition at the border of my mask. If I smooth the mask I want a softer transition.
Like Omar said it’s all about you understanding the tools and using them for your goals. In that way it’s totally valid for Martin to prefer smoothing masks opposite of the way I do it 👌
