Net clearance is good for 2nd serves in terms of safety, but you really want the ball action to give you some other advantage as well. Some slice going away or into the returner for instance, or a bounce height well above shoulder level to encourage a weak return. Ideally you'd have enough control over the spin so you could adjust to the returners adjustments. So if you hit high bouncing kickers and they decide to move back to catch them on the descent, then you can bring them in shallow and wide to take advantage of their move back, etc. I'm sure you probably know this stuff, but for me it makes a big difference if I actually practice these scenarios on a fairly regular basis.Serves 2 and 3 were mistimed and consequently lacking good vertical racquetspeed component and thus flatter. Serves 1, 4, and 5 were hit as intended and had about 3 feet of net clearance.