In other words, is there a consensus that going through a GUE class (typically DIR-F) will significantly enhance one's diving skills? OR, is it that one must PASS a GUE class to meet that standard?
Why would you think its "all or nothing". Certainly some skills might be great and others not so great in anyone. Why would they all need to meet someone else's standard in order to even be considered improved. The standard is a bar, one must get to the bar (or above) through the continuous process of improvement.
I think people improve in most good classes regardless of agency. If they don't they need to get their money back.