I have about 100 hours teaching spins... unfortunately I do not have a choice, the country I am flying in requires CPL to be taught on spin entry and recovery !!
However ... most countries around the world already took the spin training out of the mandatory training subjects for the purpose of licensing !!! Most of the fatalities (during training) happen while practicing stalls and entering intentional or unintentional spinning ... and 90% of those while the instructor is on board !!!!!!!!
I have scared myself in spins before and will unfortunately continue to do so. Practicing spins if it is not mandatory is NOT A GOOD IDEA !!! And of course with that it is obvious it is even worse when a low experience student pilot tries on his own.
Engine failures is the same... most of the flight school around the world will include in their operation manuals or SOPs "no engine failure practice during solo flights". This is so for obvious reasons. The reason an instructor practices engine failures with a student is for the student to be ready in case it happens for real during his solo flight !!!!! Not for the student to know how to simulate and practice it by himself
There are many more subjects to practice other than engine failures and spins during solo flights ... subjects that can bring a lot more to a student pilot's experience.
safety is the most important factor while flying... if it doesn't sound right chances are it is not !
cheers
Julien