You shouldn't test your response to an accident by getting yourself into one. unless you're training in a controlled environment.
If you wanna improve safety, it's better to relieve the other stressors that commonly mount on the major problem which leads to panic.
Performing only a CESA is simple. But the situations aren't usually so straightforward. OOA, badass current, lost buddy, poor viz, broken fin strap, or something as simple as water in mask can co-exist and may lead to a fatal ascent. With so many things at hand, you'll lose grip of important ones like your breathing.
So instead, prepare yourself by offloading tasks.
Of course, the higher your qualification and the more restrictions lifted, the higher the risks. It is not wise to test those limits without training.
Okay, thx. Everyone have had this training in their course. Maybe will not train it anymore after the course? Dunno