A few years ago, my wife and I took an Engage Pickleball camp. In this camp, we participated in a 3rd shot practice drill that involved three trash cans. The cans were positioned as shown below.
An outdoor trash can is usually 22 inches in diameter, so the three together as shown would be at most 66 inches, leaving about 2 feet between the net and the NVZ line (actually more than that because the middle can is up against the sides of the other cans).
However, I have only one trash can that is suitable for this drill, so I tried to position it so that a ball on the descent would land about a foot or so from the NVZ line on either side. Why is that? Landing the ball a foot from the line will force your opponent to try to take the ball out of the air, or take after it lands. Taking it out of the air may result in a pop-up, and short-hopping the ball may also result in a pop-up. However, any third shot drop that lands in the kitchen is good unless you have hit the drop shot so high the ball bounces high and can be put away.
This video (a bit tongue in cheek) shows me practicing the drop shot. The next time I do this, I will use my ball machine to make the practice drill more realistic. However, I can say that after performing this drill for about ½ hour, my third shot drops were much better when I started playing games.
Try it. Here is a video I created showing how the practice session works.