I mean its really not too hard once you get the hang of it. Lets say womens tops is a category. You find that section, pick a size to audit. I usually count out the 100 items first and section it off. Then I start checking the tags and making sure it matches the hanger nub. If I find a mismatch, I pull it out and put it on the end of my section and count the incorrect sizes later.
A well organized store will take 30 minutes. A hot mess store can take much longer. Right now, its kind of quiet so mine have been going quick.