Are you getting better on guitar, or just playing more things badly?
There are two kinds of growth we can experience on guitar. I call them Vertical & Horizontal Growth. Both are necessary, but Vertical growth is hard to come by!
Vertical Growth On Guitar
When someone who has been playing for awhile comes to me for a guitar lesson, I always try to find out why they have come to me. I ask them "What do you want to do that you can't do now."
They often say "Well, I play lots of things, but I play them all the same way. I want to learn how to do chord melody solos, more interesting chords and strums, and also improve my fingerpicking so I can try some classical. I'd also like to be able to play fast runs without missing so many notes!"
In other words, they want to move to a higher level as a player. They want to make Vertical Growth. They want to get better and be able to do things they can't do yet.
Horizontal Growth On Guitar
These players don't want to continue to learn new songs and play them the same way. That would be Horizontal Growth. Everyone can always make Horizontal Growth, even on their own. You just learn more material, but you don't actually play any differently, musically or technically. Vertical progress as a player is the tough one. It requires what is usually considered "work". I have always found it enjoyable, although challenging.
I Can't Play Anything!
Here is another even more common scenario. Someone comes in for lessons after playing for awhile, and when I ask them to play, they make a couple of excuses, and then they play really badly! Then I ask them to play something else, and they play that really badly! This is the person unable to create any Vertical Growth. They started, as we all do, with no ability, and have not been able to develop ability on guitar.
The reason they cannot raise their level as a player, is because they don't know how to practice to solve problems and achieve results. Also, because of this, there is no solid foundation of technique for Vertical Growth to be built upon. So they can only create Horizontal Growth, more things played the same way, in this case, badly.
Sadly, I have seen hundreds of would-be players in this situation.
These players have no choice but to go from song to song, and piece to piece, struggling and and mutilating all of their music as they go along. It's sad, and unnecessary.
If you love the guitar, and are dedicated to your own development as a player, if you are dying to play the way the guitarists you admire play, you must know how to create Vertical Growth. This is done through an understanding of how to practice. I am of course talking about correct practice, not repetitive "run throughs" that only re-enforce the muscle tensions causing the problems you already have.
The Good News
From my experience as a player and as a teacher, it is extremely difficult to create Vertical Growth, once bad, or insufficient practice has locked in tension and bad habits. The good news is, it is not impossible. In fact, the word difficult is not the best word. I use it only because we have such a tendency to under-estimate the intensity of concentration it takes to undo past damage. A better word is "challenging".
If you want to keep getting better and better as a guitarist, you had better learn to love challenges! As Mark Twain said "Life is one damn thing after another", and that is what playing and practicing are. One damn problem to deal with after another. But as we learn to actually deal with and solve those problems, what a sweet reward we earn.
It is not the problems we face in our playing that are really the obstacle to our growth. It is the growing feeling of frustration and helplessness we experience as time continues to go by, and we see no fundamental improvement. We start to feel helpless. We may not admit this feeling to ourselves, we only notice that, for some reason, we are beginning to lose our motivation to practice.
When we learn how to really practice, we start to feel powerful. Problems and challenges don't frighten us, they excite us. Because we know that we can look forward to those problems getting smaller and smaller, weaker and weaker, as we continue to do powerful, correct practice.
If you want to learn how to have this Vertical Growth as a regular experience for you, I invite you to look around this site further for more information about "The Principles Of Correct Practice For Guitar".