For every 20 minutes of practice time on a song, you should be working on the amount of material (in that song) that you can physically play through in 2 to 4 minutes. As a percentage of practice, you are spending 30 to 50% of your practice working on what you can actually play in 5% of your practice time. This should lead you to A) practice more and B) concentrate more time on less material. (Caveat - This is why playing in a group or with a few friends is great, too. Makes you do lots of stuff without being able to pour over it so much)
You are learning one certain song to transfer what is learned there to a thousand songs. See how what's in this piece applies to others.