Anyone here who can honestly say that they worked through all volumes (obviously not answering everything)? I often hear people talk about it but never met anyone in real life who actually did this.
The best way to view Knuth's project with these volumes is that takes in all published computer science on a particular topic, digests it, and outputs into the books some sort of "summary" of the field, or whatever he considers the most important bits, but still organized as readable/learnable textbook material, and in the way he thinks makes for best exposition. (In other words: he's doing his best to explain, and his best is very good indeed. Often Knuth's writing is clearer than the original papers, and a lot more fun.)
I read the volumes roughly 30mins a day, and try most of the exercises. Like the above linked blog post I at least attempt to just understand the question on the M[40]+ exercises which still can teach you something by merely understanding why it's a difficult problem.