Great post Steve.
I'd also add that a lot of people don't really understand how to do a fullbody workout. They have spent their lifting time on splits, and try to apply that format to a fullbody plan.
Properly getting into a fullbody program takes a little bit of time. You don't just start doing it, and bam your in it. It takes a few months for body conditioning to occur. Most people quit the fullbody format just when their body is adapting to the workload, and they are ready to seriously begin some muscle building.