Yep good stuff, I can see why it's great advise, the difference though is it's usually best to learn from your mistakes. Every skilled level designer I know has gone through stages just like yourself. It's great to try and help noobies with advise like this but there priotities will lie somewhere else. Think of it like teaching nuclear fission before learning elementary science.
My point is, level design is far more complex than slapping together a map. It's a gradual learning curve. Attempting to understand points like you state when you don't have the knowledge or experience, will confuse the living hell out of anyone.
Nevertheless good advise is always welcome ![]()