This might be more realistic with a lower playerbase, but when you had to read anywhere from 35-40 roles (or however many it would end up being), giving feedback was usually way too time consuming. You might find success in emailing/contacting whichever IMM runs the role contest you're entering to get specific feedback, but their willingness might vary.
Big thing to remember also: every IMM is going to value/look for different things in roles because it's pretty subjective. It absolutely helps to read up on role winners/runner ups to see what those people did compared to what IMM judged that month. IMM X might not want to read your 801 chapter role, but IMM Y might find it stupid entertaining.