"Snail", I fully agree, if not testing several methods thoroughly you will learn less and... indeed...use your own mind critically to find out what is valuable for yourself. "Authorities" use to change in history and novelties are mostly subjects to ( at least) three phases of reception: Being ridiculed, being resisted, being selfevident...

When I first came to (english) concertinas several "authorities" ( = old dogs ) said "You must hold it between the thumb and little finger, move the bellows in a straight line with the right hand while the left end ( if not standing) is resting on the left knee and put the strong beats on push "

They obviously did not know that the instrument was intended being held between thumb and BOTH 3rd and 4th finger and the fingerrest designed and located exactly for this purpose while the "fingering" was meant to be executed with 1st and 2nd fingers only.

After years of struggling with the old dog advise I met a chap who had done some thinking by himself and used the "four-finger-method instead. After this I systematically tried about 50 different handle concepts on a dozen of different models of instruments. The conclusion no doubt is that the handles ( both the English concept and the Anglo/Duet concept) can be significantly improved by a synthesis of them used on all types of instruments and the playing may become a lot facilitated, achieving better control of both fingering and bellowsing, along with relief of much of the strain used just to carry the instrument while making music with it.