Has any MFG researched the % of aids that are effectively fit to the patient's needs?

Figure some MFGs, would be interested in data that helps them know which sophisticated feature is actually being utilized, and also what might their products need more training support to their vendors. I am too lazy to find the ideal words to express this, but sure you get my point. With all the great tech in the new units, what is the likelihood that a patient will have them tuned to their best performance for that patient? And as a follow up, is there a common failing? Is it across the board, or does failure increase as hearing needs increase? Are less common hearing curves more likely to receive ineffective programming? Is there a particular loss that is most problematic and in need of the most skilled programmer?

What percentage of failure is due to lack of time and attention vs lack of needed testing, and or lack of knowledge?

Opinions? Tales? News? all are welcome!