I've encountered both straight and slightly bent forehands in the form of online tutorials and in lessons from tennis pros. Is one better than the other? Why the difference? One pro told me to keep my arm relatively straight and almost fully extended through contact with the racket pointing into the court after contact halfway through the follow through. Another said bent with more wrist/windshield wiper effect looking at the court through the stringbed for follow through. Again, I've seen both in books and in online instructional videos. Your experience and preference?