Ok, as a UTI graduate I can tell you this. You are right now probably going through the Hot-Rod-U course right? If not, that's random to have a discussion about dyno tuning and not be in that class.
You forget, the instructors there are supposed to teach what the industry wants you to teach, not what others have "hacked/decoded" in PCM/ECU programming to adjust values that were set forth by the manufacturer.
There actually are some PCM/ECU programs written now days by the manufacturer that use what is called a "learning" computer. It will automatically after a little bit of time re-adjust the tune to your driving style/needs. Thus if you baby your car, it will automatically de-tune your computer to give better mpg, where as you drive it like you stole it all the time, it will keep the aggresive tune that was set forth by the tuner.
Now the learning tunes can be adjusted so they will only de-tune to a certain point, and a lot of tuners will adjust that so it will only detune by a maximum of 1%-3%, this way it will keep the aggressiveness but still get better mpgs while you're not racing.
Now as far as what he said that it will automatically go back to where it needs to be, yes and no. Read above paragraph to know that.
The 12:1 is not a horsepower increase, but a fuel increase. It richens the mixture of fuel to help compensate for the added amount of air that is taken into the engine (basically anything lower than 13.5:1 is only generally seen on FI cars).
Now as far as the WOT comment, that was false. When your car goes into WOT mode, (most people don't know this) but your STFT's or front 02 sensor is no longer active. WOT will only allow the vehicle to read the MAF/MAP, and the rear 02's, and it will try to guess the proper fuel mixture needed to make the engine run properly (keep in mind that's why there is so much tuning involved in fuel and air tables). Most all of Dyno tunes are done at WOT, which is why they make much better power, HOWEVER, a dyno tune is NOT something you want to have when you are doing auto-x or anything that involves other things besides WOT all the time. Street tunes are much better for DD's as well as road courses, because there it's not all about how much power you make, but how fast and where you make it at.
I'm not degrading UTI by saying this, please don't get me wrong, but as someone who has studied performance/race cars before and after UTI as well as owning my own successful performance shop tuning a few people over the 800whp mark safely, I have a lot of knowledge and experience with this area. Someone like me who has studied this exact area for years and have worked in this area for years as well, it helps me be able to tell when others haven't been doing it that long, or are just quoting textbooks.