I have the number four cam journal grooved so it oils the rocker shaft full time and then decide, depending on which rocker arm type,valve springs and lifter type used to determine if I need to add an oil restrictor or not
Using extruded aluminum or ductile iron bushed rocker arms I don't use a restrictor, with the needle bearing roller rockers on the shafts I do use around an .040 oil restrictor with full time rocker shaft oiling