Probably a beginner paint question, but I'm a beginner.

I've been painting some interior rooms, using good quality Benjamin
Moore (mostly darker colors on the bottom half of the 6-part chip
sample) and I always seem to require at least 3 coats to make the brush
marks diappear. Even over 2 solid coats of primer. What might I be
doing wrong?

Thanks for any advice.

Janis