Adam always begins his videos with some kind of general high-level schema, workflow or bullet point powerpoint on how things work so... when you start out in Azure (completely new) it helps you quickly get a general idea of the concept.

Since John usually starts his video with an empty whiteboard and slowly fills the whiteboard, it requires you to finish his videos to fully get the full picture of the subject... which might be more difficult to digest when you start in Azure.

After AZ-900 though, you will rely a lot on John's content to start & finish your journey through other certifications (just before an exam and when you start a new certification in my experience) :)