This is only a basic rule that every trader must be respected. If the trader can not control himself in day trading then binary options will not for him. What do you think about it?
If we trade short term milos, than this rule will not be applicable as we will place more trades per day, some of them intraday, some of them with one day duration. If we lost 10$ i.e one trade we have to stop trading according this rule and if we won one trade we also have to stop, irrespectively how many new opportunities will arise in the next hours. The best way is to trade when the conditions are proper, when all the indicators and all the other signals are telling you to enter, and to not disregard this rule, but if there are more than one opportunity per day I don’t think this will be a problem to trade as long as you follow your rules.