I see quite often different robots being created to trade on any pair. However, they are never made or even tested on all major pairs. Often there’s only 1 pair and it’s made and tested on that. But traders still use it on random currencies and see totally different results. I believe it is only logical to have a EA created for one currency pair and trade with it on that one special pair all the time.

That is what Forex Brilliance authors think too and they have created a suit of EAs that trade on specific major pairs. There’s no bafflement 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 only that, when you are trading by hand you should consider that for your manual system too. It is a matter of chance, after you test and change a system on one major pair, it’s sure to perform best on it. Naturally, I do not say that there aren’t any systems that are universal, but it’s’s a lot more difficult to develop and run such a system.