Question regarding PIF



what’s should the max. and avg. pif for a dvd to be readable without glitches in most dvd players? i ask cuz I often do quality scans and the PIF average is around .4 or .5 while the max is between 12-15. It’s not low like everyone else’s, but I’ve got the newest firmware 1.uf for nec3520 and good quality media.