Star marking isn't necessary. Visual memory would do as well.
Sure, but you don't even need to memorize it, a small mark like making one star blue would do the same thing that the notches on a acrylic template does.
Did a naughty light-bulb just appear over your heard?
No, I have acrylics with notches on them, and I've never really noticed that they give me any sort of advantage, in fact I seldom even remember they're there.
Just pointing out that you could quite easily use the core set templates to do the same thing you do with the notched acrylics.