On a similar note, one of my GMing tenets is to keep in mind what's relevant to the players. I am at heart a worldbuilder, and it's easy for my imagination to spin off into the distance with a dozen new ideas, but I try to keep in mind how players will interact with the material.

People have limited attention spans and ability to keep track of things. As a player I try really hard to take notes and understand what the GM is putting out, but as a GM I really mind legibility. Sometimes the players are just clueless and you have to explicitly say your secrets.

I find it's a lot like teaching.