I'm beginning to also think that troubleshooting can't be taught. At least not to everyone. There is an instinctive property to troubleshooting that one either has or they don't. I'm not talking about using a repair manual and performing tests based on a flow chart, I'm talking about troubleshooting a circuit or building where no manual exists. It's usually something simple, but I've seen guys spend 4 hours and tear up half the building only for me to walk in an solve the problem in 5 minutes. And some of these guys are excellent electricians, they just can't solve problems, they look "too hard".