1. Learning to create different soundsDifferent scales create different sounds. By learning your scales you will learn how to create different sounds - i.e. you will start to be able to know what you are about to play will sound like before you play it.
2. Improvise up the entire neckI tend to find that a lot of students who come to me with some knowledge and experience in scales only know one position of a particular scale, or one shape from CAGED scales. This instantly limits them to playing in a single place on the neck. By learning all the positions for a set of scales, you then have the entire neck available, which increases your options. You can have more control over the pitch range you play in, you can play over a wider pitch range and you can also move between different keys more easily.
3. Use the whole neck to composeThis is a bit of a variation on the previous point, but by learning all the positions of a set of scales, you have your whole neck available to you when composing.
4. Identify the sound of scalesThis is a basic component of ear training (or aural skills) that a lot of guitar players tend to be weak on. By learning different scales and singing along to the notes you are playing, you can start to identify what scales are being used when you listen to music. This also allows you to start to recognize how to create specific emotions with your playing, which is a vital tool for any composer.
A great way to learn this is to record yourself playing some scales, or program a midi track, burn it to CD and sing along in the car on your commute. You can also do this with specific intervals and arpeggios. Steve Vai did this to practice ear training - it seemed to work pretty well for him.
5. Apply music theory concepts in your playingThis is a very useful one. By learning your scales properly over you whole fretboard, you can apply music theory concepts that you learn. For example, this week I was learning a compositional technique for resolving a suspension to a chord tone. Because I have learnt my scales very thoroughly, I could then take this piece of theoretical knowledge, put on some backing tracks, and then apply what I had learnt to my playing, in different keys, in different places all over my guitar neck.
6. Learn to visualize theory on your instrumentDid you know that your brain can't tell the difference between playing your instrument and visualizing yourself playing your instrument? An experiment was done a few years ago where a group of children were given a piano lesson. Half of them then practiced for an hour a day on the piano for a week, and half of them were sat down and had to visualize themselves practicing for an hour. After a week, both groups played to a similar standard (a gap between their skills did start to show from two weeks onwards). So the power of visualization is very powerful. I have students that visualize themselves playing when they don't have access to their guitar, and they progress very quickly at the skills they visualize.
Learning scale patterns is something that we can visualize on our instrument... and therefore, something that we can practice away from our instrument. This dramatically increases your practice time with the bonus that you don't wear out your wrists (I don't know about you, but I can't practice for more than a few hours each day before my wrists start to get sore).
About the Author:
Written by Sam Russell. If you want to quickly learn your scale patterns, you can check out Sam's free eBook, "The Ultimate Guide to the Modes of the Major, Harmonic Minor and Melodic Minor Scales" on his website.