I've done some testing with small stakes and although there is never anything that's foolproof I thought I had a system whereby I was going to win nearly every single time. I read either in this forum or somewhere else that you shouldn't be greedy so my system was to basically stop at a winner, that is laying the first fav (price between 1.50 & 3.95) in the UK greyhounds for $1 at level stakes until you're say $1 up. My testing showed that, even after a bad start with some favorites winning, the favs eventually lost and I would make my $1.
The day before I would have won $22 just laying the UK dogs if the bot kept going - I was testing so the bot did keep going.
Well, you guessed it, I was so confident that I went in with $2 stakes (so $4 profit target) but the favs kept on winning until I reached my max loss of $20
The problem with any of this sort of betting is that past performance doesn't mean a crock of *hit. Sure averages say that 30-33% of favs lose but if you get involved at the wrong time (like I usually do) this crap happens to you.
I'm back to the drawing board now and might look at making that $1 by backing the dogs or horses until I reach my goal