I use a similar approach to training, but to my knowledge it is not maximum effort from the gun which would surely lead to an implosion. Rather, it is the best possible effort over the course of three minutes. So you're trying to average the highest possible velocity you can maintain for the ENTIRE three minutes. Essentially just a 3min time trial.
Once you have this, you combine it with another one, two, or three test efforts across other durations to find your CP/CV. That CP/CV then informs training and race prescriptions based on your ability to output efforts across multiple durations.
I think circling back to the original point OP was asking about. Doing these test efforts occasionally will not erode your aerobic ability and should inform training to a more personalized level so you can target the proper CP/CV stimulus during training. One should not test super frequently, rather, test and train then test after a few weeks of that new targeted training stimulus.