Watching the doubles finals yesterday Brad Gilbert explained the pros are moving away from serve and volley to neutralize the amazing ability of pros to return every serve low and crosscourt. If a pro stays back they can crank that return shot with a forehand. Winning rec players 4.5 and lower should serve and volley 100% of the time unless they are horrible at the net but if they are they won't win at doubles anyway. Actual number of serve and volley in rec tennis that I have seen is around 50% 3.5 and rising as ratings go up. But, like I said, to win, you should serve and volley 100% of the time and if that isn't the best strategy based on a tennis player's limitations, they won't beat a serve and volley team in doubles most of the time.