I've lost most of my guitar skill having not played in over a year, but basically, I just shredded. A lot. This built my dexterity veeeeerrry quickly, but again, I basically just shredded. I rarely played any chords, and in retrospect I'm sure that stunted my development both as a guitarist and a musician. I'm a very proficient pianist and guitarist, but I'm chord-retarded, and it makes composing and improvising difficult and my products are often bland.
Also, I quit guitar mostly because I felt like I wasn't getting anywhere anymore. I was also premed at the time, so that may have contributed... but I'm no longer premed, so it's back to music with me! Anyway, don't give up because you aren't progressing at the moment. Plateaus are adaptations to a schedule. In nutrition and exercise, I espouse "confusion" because it prevents the body from reaching a plateau and instead leads to constant progressive adaptation. The same principle can probably be applied to music. Whatever your "routine" is now, forget about it for a while and practice a different way. Confuse your neuromuscular patterns and force your brain to approach your guitar playing differently. Playing the same scales constantly? Try an exotic variation. Playing the same chords/chord progressions? Voice them differently, play them in a different key, etc. Doing things consistently and constantly will invariably land you on a plateau where your brain has formed the necessary neural network to accomplish the same task(s) you keep putting before it. Being creative, devious(?), and spontaneous with your practice will force your brain to commit more of itself and different parts of itself to your music.
So I guess my advice is this:
To optimize your growth as a guitarist, play what you love (in my case, shredding like hell) because you'll get good at your favorite style and its requisite techniques. You'll have the most fun doing this, and you'll be most likely to stick with it, that is, until you reach the plateu, in which case....
...to optimize your growth as a musician, play what you love AND what you must because you'll get good at EVERYTHING, even if practicing some things is really a drag (e.g. playing Good Riddance 5000x when you can't stand the song). It will pay off, and doing some of drudge-work is a small price to pay for shortening the distance between your mind and your fingers. I wish I'd done it before I lost my guitar technique. Oh well. Back to the keyboard for me, could be worse.