I have a video on Horizontal Scales, 2 string scales (major and pentatonic) and now 3 string horizontal scales. There’s really no need to go through 4 string or 5 string horizontal scales, but these different combinations of horizontal scales all serve us a purpose… seeing our scales in different lights to open up our fretboard.
Remember to always start and end on the root note and try this with all of our scales/modes. You see the light at the end of the tunnel? You’re almost there. Fretboard mastery is at your finger tips.