The problem with so much vocal training, especially of the psychological touchy-feely kind, or even that which concentrates on breathing and postural alignment is that the central challenge in improving a singing technique is training and/or retraining specific muscle groups to perform/react/respond to the stimulus of vowel, pitch and intensity in very specific and reflexive ways. Neither touchy-feely nor breath management addresses this directly enough.
Harger Stewart, John. “Using Registral Concepts in a Voice Lesson.” Ed. Bybee, Ariel, and James E. Ford. The modern singing master: essays in honor of Cornelius L. Reid. Scarecrow Press, 2005.