I only know one archer who shoots in this way and he shoots amazingly consistently, he is also the only archer I know who can make his shoulder blades touch! Basically his draw stops at this point because he cannot move is shoulder back any further, his release is dead because he cannot follow through at all. For me the physical limit would be with my hand behind my head (the end of my follow through) with no point of contact.
I personally have never advise anyone where to anchor, instead I have said that they should get a very low poundage bow that they can hold at full draw forever, and go though twenty or so reversals with it, once they are comfortable they should come up to full draw and see where their hand is (it will almost always be close to the corner of the mouth), they can then feel where their hand is and start finding reference points ( ideally three) that will give them a consistent reference at a comfortable draw length.
One point can be rotated around, two points can be hinged but three points are solid, for me it is my index finger at the corner of my mouth, the base of the same finger (third bone from the tip) on my cheek bone and my thumb tucked under the back corner of my jaw.