Me too. I generally do all my grocery shopping during the week to avoid the crowds in the supermarkets on the weekends.

There are businesses that monitor the price of goods and sell that information to retailers, who use their competitor's prices to set their own "sale" prices.

This is why you often find stuff like tomato soup on sale at 42 cents a can...
...as long as you limit your purchase to two cans. Any more than two cans, and you pay the regular price of 60 cents a can (or whatever) for each additional can. That's done just so the store can advertise tomato soup for 42 cents a can in their flyer to draw customers in the hopes that those customers will buy other stuff while they're in the store other than two cans of tomator soup. It's called a "loss leader" where the store actually sells some stuff at a loss to get customers into the store hoping those customers will buy other stuff, thereby allowing the store to make a net profit.

Those businesses that monitor the price of goods at different stores will tell you that retailers will raise the price of their stuff prior to Black Friday or Boxing Day. The whole idea is so that they can advertise a larger price reduction in their Black Friday or Boxing Day sales flyers. So, if a computer costs $500, they'll raise the price to $750 so that they can advertise that it's 40% off when they sell it at $450 on Black Friday. While you're still getting a good price on it, it's not nearly as great a deal as the advertising would lead you to believe.

I believe that Boxing Day sales represent a better opportunity for the consumer to save. That's because retail stores know that if they don't sell something by Christmas, it's going to hang around in their inventory for a long time, and they might even have to sell stuff at cost just to get rid of the excess inventory. That's especially true with electronics where the technology changes enough in one year's time that last year's inventory is obsolete by next Christmas.

With Black Friday, stores know if they don't sell something on Black Friday, there's still a very good probability of selling it in the 3 or 4 weeks remaining before Christmas. So, it only makes sense for stores to offer their biggest savings on inventory they want to get rid of, and that means a Boxing Day sale.