What works yesterday does not necessarily work today. I have a graveyard of betting systems that have periods of winning (some with quite long periods) but have fallen into a hole. Would they return to their winning ways? Maybe. Would I use them again? Not likely unless I learn how to smell if they are turning off again. A lot of systems just don't get the returns because every man and his dog (and the dog's dog) are on the selection. So in order for any of these systems to make a comeback, the strike rate must improve or we have to get better prices and most likely both have to occur. Any of these old systems need to be checked month by month and year on year. AND if it has some big divvies and those divvies are the bulk of the profit then you are flirting with danger.