The other day the Packers got a nice play out of a screen to Mercedes Lewis, their #2 (Blocking) TE. It reminded me that we often call screens to a big play guy and I think that's a mistake. To me, screens work best when you don't run them as expected.
A former Steeler, asked what Chuck Noll would think of the hours put in by modern coaches said, "He'd be amazed that there were people so inefficient that they couldn't get everything done in a working day".
It depends. At my last school we were strictly 4 wide 2x2. We would often bring a slot in for 7 man pass pro if the defense was showing a 7 man pressure. Sometimes it would be our stud other times it would be the other slot. But we would also run slow screens from this same look. So it depends on what you do offensively and if you are able to make many things all look the same.