Iacisrmma and Avrum: Thanks so much for your answers and explanations.
What I mainly wanted to know was: Do most “Yeshivish” men (the types who are very makpid on levush in general – always wear a hat and jacket, etc.) usually keep their jackets over their Tefillin? According to what Avrum wrote, it sounds like it’s almost impossible to do so halachically, and yet Daas Yochid quoted the Kaf HaChaim that one is supposed to do so.
So I was wondering what most “Yeshivish” men do? I guess I mean Lakewood types and Chareidim in EY and Yeshiva Bochurim in both countries.