As an aside:
While the ISIS Guidelines are useful, they were not brought down the mountain carved on stone tablets. Indeed, a good proportion of the ISIS leadership doesn't follow them, which is a sore point when it comes to the ISIS courses where the instructors will often deviate from the Guidelines.
The ISIS Guidelines, like law and sausage, are something you'd rather not see being made. They are like the output of wide dynamic range neurons - there are multiple inputs that are integrated into a single output. The inputs often reflect personal bias and non-medical (e.g., economic) agendas rather than evidence. In the final analysis a lot of the literature can be argued either way so people can justify their agendas on an EBM basis. I think Nik does a good job sorting it all out and keeps it as intellectually honest as he can, but the final product has to be acceptable to the Board, not just him.
So although we can reference them and they are useful for practicing according to "acceptable standards", they are not a substitute for thought, although people do use them that way.