Do you remember when you bought or got your first guitar? I'm guessing it wasn't uncommon to find you somewhere practicing for all hours of the day and night, and yet, depending on how long you have been learning to play your six string there's a chance that your instrument may be lying somewhere gathering dust.
I find many guitar players either do not have set practice times, or are unsure of when to practice their guitar.
When a consistent practice schedule is not maintained it's easy to procrastinate and forget to practice your guitar. Next thing you know, you've entirely lost your musical momentum and wake up one morning realizing that you have not even played for weeks on end.
When practicing your guitar; a great time to learn is when you are either the most alert or the most creative. Self analyze your personal body rhythms so that you can get the most out of your practice times.
Alert Practicing Times
If you find that you are the most alert in the morning then set aside your practice times based on a morning schedule. I.e. chances are that Saturday mornings will work great for you especially if you are working early mornings during the week.
If you find that you are most alert in the evening then set aside your practice times based on an evening schedule. Just be aware of the time you practice in the evening so that you do not end up realizing that it's 3 a.m. in the morning and you have to be up at work in 3 hours.
During your alert time you can really concentrate on the super technical aspects of the guitar like improving your scale and chord speed.
Creative Practicing Times
Begin to recognize your most creative times when playing the guitar. For me, it's generally around the 9pm to 11:00 pm time. Effectively utilize your creative practice time for learning new songs, improvisation, song writing, guitar riffs, alternate tunings, and the list goes on.
In time, by consistently making time to practice; you're creative and alert practice times will propel you into another level of learning your guitar in a snap.