Larry, If I go into a transmission shop I would be talking to people with a vested interest in OTHERS not keeping their transmissions clean and in good shape...
They have a vested interest .... MONEY... even if they think they are being honest.. their memory can be affected by the fact that they will make more money from neglect of transmissions than good preventative maintenance....

AND,

They do not get a representative sample of transmission examples to work with ... people bring them a skewed sample...transmissions which are giving them problems... and with too few " N " in statistical terms ( number that each shop or each man can be assured meets the criteria which we are discussing ).. to make an informed decision as far as policy...

And the fact is that ALL of the opinions which I got from those peope would in fact be ANECDOTES.. by definition... not a controlled study of the situation...