Motion Science Shows How You Can Use Fewer Layers in After Effects by Using the Set Matte Effect
Even seasoned After Effects users sometimes have to be reminded of the set matte effect. Using a Track Matte seems more at-hand, being that you are working with layers anyway. Mattes in the timeline can get a little messy, and they certainly can increase the number of layers that you would logically need. What if you wanted to have mattes for multiple layers? What if they were using the same matte over and over?
The Set Matte effect was created just for that instance. The person behind Motion Science, Cameron Pierron shows a great example of how set-matte can be a better solution. Better still would be to copy and paste the effect with relative links so that you would only have to change attributes on one layer to have the rest take on those changes.