I'm sure the lesson is not intended as the be-all-and-end-all of perspective - its a beautifully-clearly presented example of the most basic concepts, intended as a first-step building block from which people can advance their understanding. Once you've got a concept under your belt, there's nothing to stop you running with it, to extend it and get more practice.
There are other perspective lessons here:
http://www.drawspace.com/lessons/section.php?id=e at a beginner level, and here:
http://www.drawspace.com/lessons/section.php?id=k as a little more advanced.
If you are looking for no-holds-barred advanced techniques, then I have described the choice between 1-point, 2-point, and 3-point approaches, and projective construction techniques in some of my posts here (and if you're more advanced than that, we want
you to teach
us 
)
Dave