...deletia...
I am sure that it takes a lot of training to become an Astronaught or a Doctor, but it is possible to get a pilots license in just a couple of weeks (really is not that difficult), and I once had an employee to apply for a job as a police woman, all she had to do was to pass the test and do a few pushups and situps. She did eventually get to go to a law enforcement training course, but she initially became a police officer with absolutely no training.
Sometimes we all like to think that we are super highly skilled at we we do, but the reality is that many "high skilled jobs" can be taught or learned in just a few days.
...deletia...
One time, long ago, I was asked just how something worked. I explained at length exactly how it worked. The specimen who asked then said "Well, it can't work that way so come on, how does it work?" To which I replied "It works any way you want it to work." and turned and walked off.
There are no magic beans, there are no algorithms, there is no Wizard of Oz handing out the equivalent of diplomas, medals, and testimonials. Not in digital printing. There is only experience and understanding. Neither of these are conferred, they are earned.
The first step is stop looking for the wizard and accept that, unlike being a cop which only requires that the apparatus call you a cop, or flying a plane which only requires that, in general, you know which way is up and which way isn't. Even that requires time and experience to be any good at it and not a danger to yourself and others. Digital printing requires you put in time and materials, lots of time and materials. Learning the arcanery of large format digital printing is almost entirely empirical. Some never get it.
Can you hand letter? Not make marks on media, I mean do journeyman hand lettering? If so, how long did it take you to become competent? It's a learned skill and not an innate talent. Anybody can learn do it. All it takes is years of practice. There isn't a a book or cheat sheet on the planet that will teach you how, you just have to put in the time. Successfully running a large format digital printer requires much the same effort.