Memories...cue Barbera Streisand....
https://www.bing.com/search?q=barbera+s ... 54DD448945
I remember a greyhound system called, Greyform, specifically for Hackney greyhounds. (closed 1997)
It was a "cover to win" system on the return favourite, on the first race at Hackney, on a saturday morning only. Each bet, each week, was to be calculated at 7/4. If a winner was backed less than 7/4, the remainder not won and new CTW amount had to be carried over. If a winner was backed at 7/4 or bigger, happy days, draw winnings and start afresh with initial CTW following week.
I checked previous results, losing runs were short, winning favourites were seemingly above the norm...yep, you guessed it, first 5 weeks of running the system live, all lost. Because of the long break in between bets, the sixth week required £200 or so, on the return favourite, I bottled it and it lost. Dodged a bullet and learned an early lesson when I was 20 years old or so.