When I serve I only use one ball and do not keep another ball in my pocket. It is on purpose and is not a tactic to stall or harass my opponent. The reason I do this is I tend to rush my second serve if I don't. If I take the time to go retrieve a ball from the fence or the net, I actually come back to the line with a "fresh" mindset. It basically allows me to refocus. That being said... I do not stall with this tactic. On my serve I am pretty meticulous about making sure the rest of the balls are next to the backstop/fence as close to me as possible. Get the ball. Step right up to the line. Glance to make sure opponent is ready. 3-bounce then toss and serve. It's just easier for me to refocus by taking a 5 second trip than to stand in the same spot in the batter's box. And since I am nowhere near taking long enough for a time violation, I haven't had a single complaint.