There seems to be a general consensus that high toss serves can be very effective. I usually encourage my students to practice them, even if they don’t regularly use them in matches. Part of my thinking is that, if you’re comfortable tossing the ball six feet in the air, six inches won’t be a problem.
Not all players use or even consider high toss serves. They do take some practice, but for some players it might be worth the effort. Learning any new serve can be difficult. I recall during my early training, I was being coached by Keith Evans. Keith had a beautiful double motion serve that I just could not replicate. Most of my serves were pretty unimpressive and Keith eventually taught me a basic sidespin pendulum serve. My serves eventually improved, but still remained fairly pedestrian. Now that I am coaching I can relate some to what Keith must have felt with me. Some of the players I coach struggle with serves. Others, seem to have a knack for it, enjoy working on new serves, and have already incorporated some great serves into their matches.
The players that struggle usually can’t get any energy on their serves. Serves that lack speed, spin, and deception are basically just getting the ball into play. When you consider that most rallies will only last for five shots, you can’t afford to waste your serves. A high toss might be one remedy for the low energy serve. In addition to the possibility of additional spin, the high toss may also give your serves an element of deception. Ideally, the high toss gives you more time to correctly execute your serve, and your opponent less time to read the spin and return it successfully.
Once you become comfortable with high toss serves, you will find that they are no more difficult to do than any others. Most serves that can be done with a low toss can also be done with a ball tossed several feet above your head. Most players use the high toss on their forehand serves. My own experience is that the better I feel I am playing, the higher I will tend to toss the ball. If you only use these serves occasionally, you may discover they make a nice change of pace, that can catch some of your opponents off guard. They do still need to be quality serves. Simply tossing the ball higher will not make a serve great, but it might make some average serves a little more interesting.