I see very often different expert advisors being developed to trade on any pair. However, they are never created or even tested on all major pairs. Usually there’s only one currency pair and it’s created and tested on that. But traders still use it on different currencies and see very different results. However, I I believe it is only logical to have a EA developed for one currency pair and trade with it on that one particular pair all of the time. That’s what Forex Brilliance developers think too and they have made a suit of robots that trade on specific currency pairs. There is not any confusion as regards what to trade it on and whether it should work better on one pair or another. I think more developers should use this practice.
Not just that, when you’re trading by hand you should consider that to be true for your manual system too. It is a mere matter of chance, once you test and change a system on one currency pair, it’s likely to perform better on it. Of course, I’m not saying that there aren’t any systems that are universal, but it is’s lots more hard to make and run such a robot.