One of the crowd favorite features brought in WordPress 3.3 was the ability to further customize your permalink structure to use only the postname as the slug. Prior to 3.3 this was extremely costly and didn’t scale very well, especially once your page count grew.
A stroke of genius from Otto illuminates just how this problem was solved.
Studying the URL routing of WordPress has helped me to build better websites. I think that goes for any system you use, you should really know how it works as much as you possibly can. Your quality of work will rise exponentially and everyone (including yourself) benefits from that.