Pushrod oiling becomes a need at higher spring loads so the pushrods/adjusters get enough lube. Andyf burned some pushrod cups during dyno testing. I burned some at the track using spraybar oiling only. Every setup is different, but for my money any tight lash solid, or rollercam setup with hi spring pressures(over 200 seat?) Are getting close to the edge of needing direct oiling of some sort.
