Here's a graph of attendance over the semester from a large Harvard class:
Students don't come to Friday classes. This is freakin' Harvard. It's much worse at State U.
Plus, 50 minute MWF classes are a hard way to get a lot of material covered. Between the settle down and the throat clearing and the review and the get-away, you got like 35 minutes to do real business.
There's just no need for them. Schools should go MW and T/Th and be done with it. Friday's are for seminars, grading, meeting with your advisees, and having lunch with some colleagues.