Sparring is the best way to find out if something works. You develop timing, reaction, learn to read your opponent, and learn what works best for you. In all my years of training in martial arts, I feel that my years training in boxing gyms influenced my outlook on martial arts in general. I took the method of learning in boxing and have applied it to the other combat sports I have trained in. Here is a video showing some training with pro boxers at Doraville Boxing Club in the 1990s.
Old School Sparring