Principle I: When I see a lot of folks that totally destroyed and in rehab mode, one of the big reasons they are there in the first place is because they train like a buffoon. Now for the general population, program design is a mode of efficiency. There are many versions of okay.
But when people pick dumbass exercises and train with bad form, they go from a trainee to a patient. And they probably get fat and weak.
Principle II: When you have the time and/or means to have multiple clinicians working with you, say a PT that can treat your pain and dysfunction and a trainer or coach that can further train the dysfunction and fitness, you are ahead of the curve. But many coaches are not allowed or capable to help with serious issues and pain. On the flip side, the closest some PTs and Chiros have come to understanding training is the first semester of therapeutic exercises, which of course highlights methods that were old in 1984.
Principle III: When you can get this level of access to someone of Eric Cressey’s ilk showing you how to train with as much variable control as distance training can allow, and you can do it for half price, I’d like to think Principles I and II are not so paramount anymore.