All Cal Newport's advice is pretty mundane and, frankly, feels almost exploitative these days. "Let's give those distracted folks some old-as-sin observation, but packaged as new", it looks like he is saying.

Deep Work = find a place with no distraction and work for a few hours with real focus.

Einstein Principle = focus on a few things.

Is there anyone in the world who thinks that in order to achieve excellent results (unprecedented, surprising, miraculous) from research and similar intellectual endeavors, it is better to divide attention and focus among many "projects"? I don't think so.

In other professions, better results would be accomplished by diffusing attention (think of the Director or VP level in large tech companies, which are the companies I know the most about).