>>5862668DaB just doesn't teach the necessary material. You need very high accuracy to build recognizable constructions but he completely ignores that aspect of drawing, despite being marketed towards beginners.
I went partway through lesson 4, mostly helped along by other resources (Keys/Loomis) and just stopped DaB because I realized it was strictly worse than almost every other resource. The demos are alright but you can watch Han/Vlippu do the same stuff.
DaB has some very arbitrary rules such as additive construction only, no deviation from guidelines, and cast shadow textures; which as far as I can tell are only found in DaB and have no justification.
Textures are a great example of why DaB sucks. Peter Han's homework is to draw several pages of small strips of textures, starting with hatching and progressing into reference inspired patterns. DaB wants you to do only 3 different textures, but over huge areas in a painstaking cast-shadow only excercise that will probably take 4-6 hours minimum and is a massive filter for beginners.
In that time you could do 50+ Han textures, which excercise will teach you more?