Today I was visiting a store as I was interested in seeing if there was anything good before they change the sales as the next day was the new flyers, which I happened to have seen on the company site already as well. To my surprise there were actually some items that were supposed to be on sale tomorrow that were being displayed today. Whether or not that was intentional I am unsure.
However, I know many times employees at stores simply see a big shipments and assume that they need to put it out on the floor right away. Therefore, since the items are already registered in the system people can still actually buy it at the discounted prices. Sometimes too if it is a bunch of low priced items businesses will just throw them out of the floor a day before for the sake of having less to put up on the actual sale day.
This rarely happens for high ticketed items as it’s usually more obvious when someone has put that out earlier than the intended launch date. But either way, being aware of what the next flyer is the day before can at times enable you to get the same sale prices faster as you never know what could be on sale already.