The key is that the players must spend 50% of their practice time on learning all types of serves and then applying it in pointplay situations. In the coaching camps I observe that too much time is spent on ground strokes and very little on serve. We all know that a point does not start with a ground stroke, it starts with a serve.
The serve should be practiced in two segments:
1. Serving from the basket to various targets, (spin control, heights), etc., and
2. Pointplay situations, practice sets, etc.
For example, in pointplay situations the following discipline may be followed:
Playpoints or a set with the following rule:
If you win the point with a volley and/or a smash you win 4 points. If you win the point from the baseline you win just 1 point.
This will improve the other essential area such as approach shots because without quality approach shot you can't have a decent first volley.