There's not a lot explicitly wrong with this article, but there isn't a lot right about it either. One of these days I'm going to have to write a proper mapping tutorial. There's way more to making a good map than this article or any of the previous tutorials go into. Nobody ever talks about structure, or balancing out spaces, or where it's okay to break the rules, etc. at a length that allows anyone to learn anything. If you don't understand the underlying "artsy" space utilization and how to structure your map so that it makes for good gameplay, it doesn't matter if you use the right tree shadows or movement permissions, your map's gonna suck. Maybe this break I'll spend a few hours and write something like that up for the community.
Just as a side note, it took me 4.5 hours to map out a route I did recently. That's not including the time it took to passively mull over how to make my concept work and draw out a basic sketch on actual paper. Sure, my maps are huge, but if you have a decent sized map and took less than an hour on it, you didn't do it right.