Then I spent some time at UBI in a bike mechanic class. The guy who taught the section on derailleurs commented that he had never found tinkering with B Screw to have a meaningful effect on derailleur function
As in he was saying it would not effect the derailuers performance? because I could understand saying that. But if my teacher at UBI had said the b-tension screw had no function I would have asked for a refund and left