I would agree that after visualizing the different scales,the chromatic scale appears before us,we can conclude that any of the twelve tones could work.This is entirely true so skip back to how you identify these scales individually.
The major scale for all practical reasons has all the different sounds that a person might find handy.C major =cdefgabc // D dorian=defgabcd //E phygian =efgabcde //F lydian =f gabcdef //G mixlydian = gabcdefg // A aolein = abcdefga //B locrian = bcdefgab and so there are your 7 modes off the major scale.
From a starting point of say C major {ionian mode} you can build a major or none dissanant
sound.You can use this sound as a constanant,for continuance in motion,keeping an even texture in your sound.As your riff builds think of this building as levels of push and pull or constanance and dissanance or even tension and release.I personally feel this a choiuce by the artist themself to deside although schools of thought might lead you to believe a particular idea is better.
Starting at C-D this interval is called maj 2nd or whole step giving a sound that is constanant
in sound.You can then pull this sound to tension by dropping back a half step or one fret back to add tension.Also you can slide back up or drop back down one more fret to resolve this tension.
This brings us to our starting point again to allow us to end riff or build again more movement in our solo.Quickly jumping forward if you were to play your riff thru C major scale to alter the 7th
step down one half step this 7th step, B note, would become Bb giving us then the C lydian mode.
This is simply a tool for a sound nothing more unless you want to be so anal that there is only one truly perfect sound taught only one perfect way. Ikesws