I used to run reliable EAs on multiple charts with my logic being... the more charts in use, the more opportunities that will come to me. Then I realized this was a drawback for me. I wasn't willing to open so many trades on so many pairs. Because of this, if an opportunity/setup didn't pan out for me, I might jump to another pair and attempt it again at a new opportunity, but then because I wasn't playing that pair ongoingly that opportunity might also be one of the loosing ones. Tricky to explain. I also found it time consuming monitoring so many pairs and trying to keep track of what is going on on each pair. So I finally submitted to using just 2 or 3 pairs and sticking to those. No prob if an opportunity didn't pan out... I know others will come along on the same pair if I am patient (instead of keep switching over to other new pairs). My success rate actually improved after this by sticking to two or three pairs only. I also found it less stressful and easier to manage, which I feel does affect one's success skills as a beginner. But please note, I am only a 3 month-old trader... thus a beginner myself. Therefore this is only my personal experience and my own personal opinion.