The question is not if you should have a maxloss for the day but how much it should be, especially if you're a discretionary trader. Setting the limit above your normal intraday drawdown is a good start.
I believe this is a smart way to trade especially for newbies keeping your losses in check will always be a big part of improving your trading skills.
if i'm willing to lose X$'s on any given day, my goal trading is to make at least 1/4X$'s but hoping to get to 1/2-2/3X$'s- with maybe one or two days a month equaling X$'s. it has worked for me well
max daily loss is a MUST. I used to give back weeks of profit just because I didnt have a daily loss in place. As for the max gain for a day, I disagree with that one. If you have an edge, it should be put to use whenever the situation occurs. In Market Wizards there was a fund manager that was up 100% on the year and considered booking the year, but a friend convinced him to keep going and he ended up over 400% for the year. Trading is mentally easier when you have already made decent money.
Loss, yes...Gain, no. When you are new you want to stay in the game long enough to learn how to extract profits. If, in your inexperience, you blow out your acct too quickly, that may be the end of it. Takes time to learn. At the same time, having a daily goal to the upside puts your focus on the money and not "trading well". If you trade well, the money will come so no sense on focusing on the end result but rather the process.
The only way to limit fear is by using and honoring stop losses on every trade and for every day. And the only way to limit greed is by using a profit target on every trade and for every day. Using loss/gain limits for the day is a good way to reduce the emotional volatility of trading.
Why especially for newbies?? I think this should apply to anybody who trades short term. Paul Rotter when interviewed by Trader monthly 4 years ago said he always has a max stop loss for the day.