I see very often different EAs being created to trade on any currency pair. However, they are never made or perhaps tested on all currency pairs. Typically there’s only 1 currency pair and it’s created and tested on that. But traders still use it on random currencies and see absolutely different results. I suspect it is only sensible to have a expert advisor made for one currency pair and trade with it on that one actual pair all the time.
That is what Forex Brilliance creators think too and they have developed a suit of EAs that trade on particular currency pairs. There is not any confusion in regards to what to trade it on and whether it should work better on one currency pair or another. I think more developers should use this practice. Not only that, when you’re trading manually, you need to consider that to be true for your manual system as well . It’s a mere matter of probability, after you test and modify a system on one major pair, it’s sure to perform best on it. Of course, I’m not saying that there are no systems that are universal, but it is’s lots more tricky to develop and run such a system.