Well said Barney!
How else would you know if your system works if you do not
"BACKTEST !!!!!"?

Huge difference!

Also, Lately I see some posters here saying that is OK for a system to lose for some time, and it's the "long run" (nobody dares to specify how long is too long but) that matters.

Utter ****, Yes you can have a losing day or two, three even, but any more than that and I would question what's happening?

The only answer can be that you are betting on races-horses
outside the system's researched and proven parameters or those parameters are loosely defined and accept races and horses it wasn't supposed to.

Remember when children spill a bag of candy in the dust?
First they pick up the cleanest, etc... in the end most of the candy gets eaten, same as most of the horses will be bet by most punters system or not!

Or just lack of discipline,

Good luck

**** ?????