large shops and small try to have as little stock as possable and use just in time delivery. this is because stock on shelves ties up money, less stock means more profit

after working in a supermarket warehouse asda/walmart for 9 years i can tell you we always had at least 800 lines of 33,000 out of stock at any given time. most this down to central distrobution warehouse out of stocks thanks to there just in time ordering from suppliers. the idea of just in time ordering is great but in practise it is a nightmare the computer controls set by central office fail to take into account that small increases in sales can cause people to think stock is short with half full shelf and they buy acouple extras to tide themselves over.

cookery shows and recipes in magazines and newspapers even the net can cause whole sections to be stripped in hours.

i use to do the stock and order manually so last years sales plus 5-7% was the standard depending on the line. now it is last years order plus 1% by the computers. lowers stock holding but does tend to leave alot of gaps.