In my mind, there is no doubt that mastering wedding photography is THE best training for ANY photographer.
Every wedding is chaos! And as a photographer, you have to deal with that. And get the job done. And not only that but do a great job. Every shot is against the clock, you’re working with inflexible often fragile temperaments and you simply have one shot at it. You learn to excel at family portraiture, fashion/editorial photography, photo journalism, still lifes, incorporate elements of sports photography, product photography, interiors and landscape photography. Lighting conditions are constantly changing from one shot to the next, sometimes by the second, which forces your technical knowledge of lighting to the level of unconscious competence.
As a person, you learn to be diplomatic yet assertive, confident yet humble, plan for the worst yet remain overwhelmingly positive in front of everyone you encounter.
An accomplished wedding photographer can invariably turn his hand to any genre of photography and make a great job of it. The same cannot often be said of a photographer from any other genre trying his hand at wedding photography.