Just my 2.0c
By it's very nature all forms of training have to be general rather than specific in other words you will learn a lot more than you really need to know for the task you have in hand. A good example of this is:- I use many different design programs which create the GCode automatically using a post processor therefore I only need a minimal working knowledge of GCode to get by. So in my case, taking a GCode training course would be interesting but hardly necessary. It is pretty much the same with electronics, most of the stuff associated with CNC is digital and there is little to be gained learning analog formulae and theory. I am not trying to discourage learning, far from it, it is just that 'hands on' experience targets the exact areas where learning is necessary.
I think that what I am trying to say here is that there is no substitute for practical experience - as soon as you come up against something that you don't know then research it to find out. This way time, which when it comes to CNC there is never enough of, is not lost.
Tweakie.