ninjanoir789 so don't need to pull update some times a week like with LOS, cause they have a nighlty build
It might make sense to start from a statement of the desired outcomes. For example, building some pre-release snapshot of GrapheneOS several times a week will definitely consume some CPU time, wear some storage device out a bit, etc. If that results in a desired outcome, that's fine, but it's not yet clear what the desired outcome(s) might be.
To get the latest developer-tested general-user release candidate, just switching System Updater to the alpha-release channel suffices. Building GrapheneOS is generally done by people who wish to modify it, not by people who wish to keep up to date.