The key to success is to work through a new detector yourself and not rely on random people on the internet. Granted, not everything he highlights is incorrect (a broken clock is right twice a day), but run the tests yourself that are worth running and see if you get different results. The only thing bigger than his draw is his ego, he puts in time so people like you can place him on a pedestal and feed that hungry ego of his. He goes into tests with an endstate in mind and structures the tests to get a result he is looking for. But hey, if it works for you then that is all that matters.
A detectorist will learn more getting off the bench and spending that first 50-100 hours digging all those iffy and weird signals to see what the machine is doing. That will give you more detector knowledge than watching contrived bench testing. Both those Shillbillys aren't in the hobby for detecting, they are in it for bench testing to feed their egos.