I see fairly often different expert advisors being made to trade on any pair. They’re never made or perhaps tested on all currency pairs. Often there’s only 1 currency pair and it’s made and tested on it. But traders still use it on random currencies and see very different results. I think it is only sensible to have a EA developed for one currency pair and trade with it on that one particular pair all of the time.
That is what Forex Brilliance review authors think too and they have made a suit of expert advisors that trade on explicit major pairs. There’s no perplexity 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 by hand you need to consider that for your manual system too. It is a matter of possibility, when you test and change a system on one pair, it’s sure to perform best on it. Naturally, I don’t say that there aren’t any systems that are universal, but it’s’s lots more difficult to make and run such a EA.