This is only my own experience, about 20 years ago I developed a PLACE betting system that showed a tiny profit of around 4% on t/o, I'll have to admit it was hard to follow through the peaks and troughs but in the end always came about the same, I reached a max of $100 bets. Then got some big ideas, In can tell you as the stakes increased so did the meagre POT. i.e. at first I couldn't believe it but my (what was modest stakes in the scheme of things) were actually affecting the dividends, eventually to the point where it became unprofitable, I haven't found anything that can make a profit LONG term since!