'That is nothing to do with how many pairs you are open.' - Was that directed at my post? If so, please elaborate, I don't see how your reply on MM has anything to do with what I explained. Your risk increases proportionally to the amount of trades you open (if you use your method - 'each trade'), the correct, advised method is actually max 2% equity (not balance) for beginners and max 5% for experienced traders on ALL open positions, though I know of a few experienced traders that are pushing 10%. So it would make sense that if you found 10 trading opportunities on 20 pairs vs. 5 on 10 pairs, you effectively have increased your risk by 100% without the need to calculate anything based on your method.
Regardless, my point was that you open yourself up to entering more trades the more pairs you watch, thereby increasing your risk and lowering available margins... no use in seeing an explosive setup on a pair you know is going to make great moves and you have over extended your margins.
For every loss there should be at least an equal and opposite profit.