Should we change an effective serve

Hi, Jeff and Alois

One player at my club told me that in one game that I should have one I had been doing wrong with my tomahawk serve.

My tomahawk serve worked quite well and I even won some points with the serve. But this player told me that instead of serving it so insistantly I should have served other sevrices too even if they had not been as effective not to let my opponent adjust to my tomahawk serve.

So, I want to ask you how often should a player vary his effective serve which gains him advantage in the point to keep the opponent unconfident at reception. Or maybe there is no need in changing a good serve if the opponent receives it ineffectively.

Thanks in advance, Evgeny, Moscow.