I've had the fortunate/unfortunate (you choose) opportunity to operate a huge variety of equipment in my life. One of the more difficult to master; I mean get really precise and quick with, was a 100k plus excavator. I'd had a couple hundred hours on a 50k machine and figured that it would be exactly the same, only it would work faster and move bigger things. It's hard to explain, but it was just different. I'd say that the average guy who can run a tractor with an FEL without thinking about what he is doing can learn to be relatively capable on an excavator in a couple of days worth of work. The problem is that, in the original poster's case, an experienced operator would be in and out, having done a better job, in far less time than that.
There is also the example of when you think you can operate a piece of equipment properly and when you really can. Take for instance a Cat D11 dozer. With all the new electronics and everything, they are actually quite easy to do basic things with one. The problem is that you can make a
huge mess rather quickly, and keep making things worse even faster trying to clean up your mess. I was shown how to make a couple of passes by huge oak trees with the rear ripper down to rip the roots loose. Now, these trees were so big that a 36" bar on a chain saw would not have been nearly enough to cut them in half. Then, after the roots are ripped, simply put the blade into the tree a few feet off the ground, pour the power to the tracks, and lift on the blade. Pop, and over goes the huge tree away from the dozer and all is well. As people seem to do, I got a bit lazy and found that I could do the same thing without ripping the roots much. Hey, big powerful dozer, and it was fun. That was until I pushed over an absolutely huge oak and the root ball came up between the front blade and the dozer.
I'm talking 6 hours later with almost 10 acres destroyed and I'm still backing in circles across ditches, smashing other trees etc. trying to turn loose of that darn tree!!

Rather than waste even more time I had to get my chain saw and spend a couple of hours hacking away at roots to get it loose. So, I thought I knew how to properly operate that piece of equipment, but I really didn't.
