Here are a few more thoughts on the topic. I hope you find this useful RobbieZ.
We all become periodically despondent with our (lack of) progress. In that space, it's easy to feel isolated and start questioning everything you thought you know about playing guitar. The fact is that the greats we admire were even more isolated than us today. They did not have that wealth of resources at their fingertips like we do. For the majority of them, their early learning was limited to mimicking recordings.
George Benson and Eric Clapton will be the first to admit that they are not theoretically minded guitarists. They play what they know. I don't imagine either of them playing West-African grooves very well, for example. That's not what they know. For them to know it, they have to practice it - just like us.
Guitar playing is a very versatile activity, with constant room for improvement across a very wide spectrum of elements and styles. So no-one ever knows if he knows enough or if he is focusing on the "right things" during practice. Beating yourself up about the things you don't know will drive you nuts and is no good for your confidence. Therefore I've learned to focus on doing the things I can do, better. The rest I learn by necessity. And here is where clear goal-setting makes another appearance.
If my goal is to play an epic song that is obviously out of my league, I have to learn to master the elements of that
song. It could contain fast runs, sweeps, pinch harmonics and all sorts of other horrible things I struggle with or know nothing about. Nevertheless, these things then become my current curriculum out of necessity... brought about by my goal.
If my band gets booked for a wedding gig and the bride pre-requests a specific ballad as a first-dance song, then learning that song becomes a goal and all it's components become my current curriculum.
If it's my goal to jam with highly skilled jazz cats at a local jam night, then preparing two windgat jazz standards
and a killer solo for each, becomes my goal and brushing up on my comping, modes, favourite jazzy licks, etc become my current curriculum.
In this way my learning is goal-oriented and has real-world relevance. At the moment, I am working on Christmas carols, for example. Simply because 'tis the season.