As a sadder but wiser person I would say yes.
I thought I had a great quinella system going. It averaged about 14% Profit on turnover over a period of 10 years betting on probably a third to a half of the races on offer. I watched it for two months not spending any money and it was almost embarrassingly successful. That was up to November last year. I started putting money into it in December and by early January I had lost my nerve and half my bank it lost so badly. It was a very volatile system too. I followed it up to the start of March and it lost consistently week to week so I lost interest. I actually started watching it again last weekend and it ran at 100% profit both days of the weekend and just in front today.
I should have done my stats a bit more thoroughly but I was lulled into a false sense of security by a couple of great months when I happened to start live testing.
Maybe half way between Crash's "Get into it before it falls over" and Marcus's "You must find out why it has losing sequences" there is some ground your comfortable with.

Don't know why I wrote all that - it's all waffle really. Sorry mate, you'll have to make your own mind up.

KV