Questions about how often to do scans and about Norton Power Eraser

Hello, under run scans theres 6 kinds of scans if you will?, the last one is facebook related but since I don't have fb this scan doesn't concern me. How often should I run the scans? theres quick scan, full system scan, custom scan and custom task, how often do I use them especially quick scan and full system scan, everytime I do quick scan which is like 2 times  day it detects and removes cookies? so since everytime I do a quick scan it detects cookies it makes me want to do a quick scan constantly . How do I know if I need to use Norton power eraser and how often should I use it?. How often do I use Run LiveUpdate

Thanks