Scales themselves are really only good for finger exercises. But what studying the scales allows you to do is know the notes in a certain key (in the key of F the notes are: F G A Bb C D E F, etc...). This is important for many theory things, but probably most importantly for solos (impov, pa'ani). If you know the notes, you can stay "on the road" when you do a solo and not hit "unwanted" sounds. Just playing a scale is not a solo. You have to play a unique note and rhythm order for it to constitute as a solo.