Yes, "rehab can last a year or more." Is that still the general rule these days?
My son's mid-80s pitching speed began falling in his HS senior year. Rest no longer helped much. One of his older teammates had TJ surgery and I recall his PT/rehab took about a year. He was a mediocre pitcher, but an impressive 6' 5" and a starting forward on our HS basketball team. I inquired about his TJ and the kid said the operation wasn't too painful.
We considered surgery, but never did it. Son got a Juco baseball scholarship and played/coached some summer American Legion ball. For him, the highlight was getting paid (fairly well) to coach Legion baseball, his first real "job."