Depends on what The Riff needs. If its strong as is then no I stick with it maybe in multiple octaves while giving some variety in rhythm.ok, so if a riff is using the root, b3 and 5 which implies a minor scale, would you build a bassline focusing on those 3 intervals or would you expand it and use other notes from the minor scale?
If The Riff isn't as strong more of the scale gets used in consistent and regular rhythm, but I'll do it over the space of the riff being repeated 3-4 times. I try to think of deviations like this as lyrical or singsong.
Then again I prefer more verse-chorus-verse or 12bar as opposed to how free form Monobrow is. So take this all at face value. I have no idea what works best for you.