A little while back, I wrote a post highlighting the need to serve earlier in practices - check out that article here.
I also discussed this on the BTS podcast with PhD in Sport Science, Jaime Fernandez, who recently published a research paper on this exact topic. His conclusion - serving should happen at some point in the first half of a tennis practice AND NOT at the very end of a session. This will benefit players both from a development standpoint and from an injury mitigation point of view.
