A. It seems (to me) a commonly held/believed/accepted practice that it is wise to Repair Permissions prior to installing an OS Update. MacFixIt may also endorse this practice, but of that I am uncertain.
B. I have also read (source unknown) that Repairing Permission prior to an OS install is a waste of time because the installer runs as root and thus does not affect permissions.
(Repairing Permissions after the OS install is not at issue.)
So, is “A†a techo-myth or is “B†correct? Or, maybe neither?