121.5 Codswallop
I have never done a practice pan on 121.5 as part of any of my flying training, those who think it is wrong of FTOs not to teach it (practically) have obviously never learnt to fly (real flying, resulting in a license!)
Firstly, A lot of training is theoretical as you can't practice everything in the air.
Secondly, we are taught to A.N.C. As long as we can fly the aircraft in any emergency - which IS taught practically - telling someone about it comes last.
I had an actual pan as a student on a solo navex - nothing serious, but my instructor had taught me well enough to remain calm, fly the aircraft to a suitable airfield and call a pan on my current frequency (Liverpool App).
What would I do in a mayday situation?
"My engine's failed!!!! How do I tell D&D????"
or
"My engine's failed!!!! How do I land safely????"
Aviate - Navigate - Communicate.