The author predicts they will generally take only one aggressive trade per day, using all available buying power, most likely before the market open (9:30 AM), leaving them unable to trade further until the next day due to settled cash rules.
"I really can only trade if I'm going to go aggressive only once a day and that means that I'm going to use all of my buying power on one trade... most likely by the time the bell rings at 9:30 I will have already taken my one and only trade for the day and I'm going to be out of buying power and have to wait I'm G to have to wait till tomorrow"