Tossing high is generally what we've all been taught or learned. I personally also toss the ball fairly high on my serves because it's habit for me now. I was hitting just earlier today and a pretty difficult time dealing with my opponent's serves. It wasn't because his serves were fast or anything but his service motion was fast and that really caught me off guard the first set. A lot of replies in Tennis are replies to anticipations. Meaning that if you just leave it up to your reactions to react at the very last second, your shot quality and consistency will be fairly poor. There is such a thing in Tennis, as we all know, called preparation and that requires anticipation and guessing. What really caught me off guard about my opponent's serves is that his toss was quite low, meaning that he made contact with the ball very soon after the ball leaves his hand...I don't think his ball ever reached its apex. Even though his serves were only "okay" in terms of pace, he did manage to ace me a few times just because I couldn't anticipate and prepare for a service return. If I had to guess, I'd say his 1st serves were only around 80mph. I have dealt with serves around the 110mph+ when I was college and even though the pace was fast, my opponents all had a pretty good wind-up and that always helped me anticipate and react to those fast serves. The more I think about it, the more I see how a short toss and a quick service motion can really help you out. A shorter ball toss would also mean that it's less affected by outdoor conditions as well as being less affected by toss irregularities. It's just a simple, more straightforward motion and the advantage of that just means more consistency, due to less "body" being involved in the execution of the stroke. Long, loopy toss with a long, complicated windup has more room for errors in my book. Don't get me wrong. I don't mean a service motion that's "rushed" or anything like that at all. There's a difference between short, abbreviated motion and just simply rushing your strokes.