0% of that happened with a safety pilot, but all of that and more happened in the prep leading up to the formal training, and then some of it happened again with the CFII within those 15 hours.
Just as well, because years later, I did have an engine failure at 11k in IMC (got it back at 7500ft or so), and a while after that, a separate failure at 3k in IMC, got it back at 1700ft. Vacuum failure (VMC on an IFR flight plan), and alternator failure, too (these were spread out, thankfully, or it would've been quite a day).
Have done the diversion thing quite a few times since getting the ticket, one required the construction of Plan D on the fly when Plans A, B and C all failed in epic fashion. Plan D was to land at Teterboro.
Your point is well-taken, though, if a student had zero prep beyond the 3 hours of hood time from the PPL, I could see that it would be a struggle to get it done in 15 hours of dual instruction. My point stands from the previous long post, though. If we agree that it takes quite a bit of time and exposure to flying in the system to become proficient. Much of that time can be amassed without a CFII, and then use the CFII time wisely to verify that everything is in place.
There's an instructor named Al Waterloo, I think he's working with Cirrus now, but he used to LOVE when students arrived having prepped for their training in this manner. They'd use the time they had to go fly a bunch of really long XC's to a wide variety of airports to build a body of experience that most people rarely get in their IFR training, and, of course, he'd check for bad habits that might have been acquired along the way.
To that point, when I did show up for my first day of training (I actually ended up with two different instructors as the first was in a car accident and had to stop flying for quite a long time), I gave the guy some background and said, "I hope that I've built a body of knowledge that will be useful here, but it's all theoretical thus far, none of it's been vetted. I'm totally open to the fact that I might be full of crap." He laughed and said, "we'll find out pretty quickly." He grilled me on a bunch of stuff on the ground (best place to talk about it, really), it went well. Then we flew. That went fine, too, although I did get hot and sick by the end of it, so we called it early.
I hadn't been studying exhaustively prior to that point. That is to say, I went into high gear with the self-study once we DID start the formal training and learned quite a few new things, but I pretty much learned them at home from various reading materials, not in the cockpit with the CFII.
If memory serves, the only meaningful things that DID come up in the cockpit were a range of approach speeds, when to configure, precision vs non-precision technique, dive and drive vs constant descent etc. They were all important, to be sure, but we encountered them and covered them pretty quickly. Notice I'm not arguing for a reduction to zero time with an instructor
All of those things got hammered out in first 1-2 flights, then he sent me on my way to Safety Pilot World (this as in a flying club, he knew the other pilots, recommending one or two in particular).
