I am fully convinced that is as simply as "cut losses, let profits run". This trading is not easy but I think it is easier than we allow it to be; our thoughts and thinking get in the way of our reacting. I keep a trade by trade journal for one account and a daily trade journal for another account. Going back over it the thing that continues to arise is to "cut losses and let profits run". The other is to take the trade setups that are there. I do not believe in a daily stop, if the system is good, or your trade method is good, then take all the signals and let the stop sort out the bad ones. I believe most of the time we beat ourselves at this game until we master our emotions.
That would go a long towards explaining that horrifying 90% losers "statistic" (the jury's out the accuracy of it, imo) Is your statement that "most daytraders have a very high percentage of winning trades" just an assumption, or have you actually investigated this and reached that conclusion? (I'm not being sarcastic, I really am interested to know) I know in my case that even on my best winning days my win percentage is hardly ever over 65%, I've had the odd 80% day (few and far between), my normal winning day is 50-60%winners, normal losing day is 35-40%, also some "horror days" where the 8 of the first 10 are losers, at which point I quit for the day - very rare, and the total dollar loss is about the same as a decent winning day, so it doesn't blow out a week's worth of trading. Gotta play good defense baby - keeps ya in the game. Just like my beloved Bad Boys (two time world champion Pistons)
I think gain limits are silly... When you understand the market dynamics, TAKE ADVANTAGE. (Daily limits are somewhat understandable; you might get emotional... but you really should be over it by the next morning, at least)