There is a big difference between your beaches on the east coast and our beaches here on the west side. What you are suggesting is true if your on the east coast. I hunt in the Miami area six or more times a year. Storms make big changes on your beaches and stir the pot exposing new targets that have just been hidden by deep sand. In just a short distance off shore your waters go deep, but on the west coast you have to go out twenty miles to hit deep waters and then they are only half as deep as yours. Last year your winds ran on shore most of the summer and resulted in loss of sand in some places up to the sea walls exposing tons of targets. It was the same in Palm Beach and all the way up at Daytona. I know because I hunted most of the east coast of Florida.
I've been hunting going on twenty years. I have hunted in NewEngland and LA and most places in between. What I have learned is that ever beach geographically is different in simple ways. West coast beaches are some of the most stable types, or in other words, you can can hunt them year after year and always know what to expect. The exception to that would be the after effects of a hurricane or city beach replenishment projects.
Your theory's seem right for your beaches, but have nothing to do with our beaches. Explanation: If we have a storm out of the west, tons of sand is pushed in and covers up targets with two to three foot of sand. It can take months to move all that sand back out to sea. When this happens, you can't find any targets unless they were dropped today. The term for that is "Our beaches are sanded in". The sand I'm talking about doesn't even have shells in it, not even small pieces of shell, so what are the chances that the storm might choose to pick up hundreds of pennies, nothing else, and drop all of them on the most congested part of our beaches? No Rings, No Silver, No Pull Tabs, No steel, and not even one sinker, just sand and in an effort to be nice to detector people, it lays all those pennies right on top of the sand so that we wont miss them.
I don't mean to show any disrespect to any of your comments here, and I'm sure that pennies show up on your beaches just like you say and you seem good with that, OK, I get it.
That is not what happened here.