I have been in a rut for weeks, and finally feel like I'm coming out of it and it feels fantastic. It's not so much that I've made any leap in skills, just that I've started to feel the joy of playing again after a period of feeling frustrated.
Tonight I sat on my guitar stool and closed my eyes and just strummed C, G, A, D at 60 bpm again and again for about 20 minutes. I think I opened my eyes and adjusted my hand once or twice, but otherwise just kept my eyes closed and stayed relaxed and focused on hitting those 4 chords really cleanly without looking. It felt really nice, and my fingers were really starting to feel those chords as whole shapes instead of individual fingers.
My chords have been feeling sloppy lately (especially A and D) as I've been trying to keep up with songs, and I've been really unhappy with both the sound of the chords and my inability to keep up the pace. Just playing C, G, A, D again and again with my eyes closed was so relaxing.
To be honest, I only stopped because my wife wanted to go to bed and get some sleep.
It takes as long as it takes unless you quit - then it takes forever and you will never get there.