I tried your system and I believe it does work if one thing is understood. Playing a C major scale from the root C, isnt playing or learning the G mixolydian. For one who already knows the major and minor scales, and is looking for a easy way to find the modes. It is a good way to find the notes of the G mixolydian scale (mode) on the fretboard by playing th C major scale. How Pentatonics relate to this, I am still not seeing. I dunno. To me, Pentatonics are just five note scales that work well with the root you are harmonizing over. Without writting too much about them. Penta 'means five' and tonic 'means root'.

I use modes, more than I think most people, as harmonizing certain chords and also as a transport scale to get from one key to the next. Since some chords don't modulate natural with other scales, I'll use a mode. An example is a diminished chord, there is only one in each major or minor key so you can't modulate naturally between keys. I'll bring in a mode to accomplish this. The easiest example is the Locrian mode, since it contains the formula 1, b3, b5. The formula of a diminished chord. So if I end a locrian scale run on the root, I can start the new key on that diminshed chord. Starting a chord progression on the diminished chord is a good way to build an outro.