If travelers haven't figured it out by now, airlines don't like to distinguish themselves from each other by much. This is why there have been a dozen attempted fare hikes this year: If one carrier hikes fares and the others refuse, it won't take. "Airlines have one overriding mantra right now: Never be one dollar more or less then my competitor," Seaney says. "If they're one dollar more than their competitor, they're on Page 5 of comparison shopping results." The same rule applies to airline sales, which go through a very regimented process before they reach a consumer. Airlines can change airfares during standardized fees three times a day: At 10 a.m., 1 p.m. and 8 p.m. EST. It usually takes two hours for those changes to post, so when airlines put out a last-minute sale on Monday -- as is usually the case -- the resulting series of events makes 3 p.m. EST prime time for finding discounted airfares. "The 8 p.m. feed on Monday is when an airline posts a sale," Seaney says. "The others carriers will file at 10 a.m. and 1 p.m. the next day to match, and it takes two hours to process." That's not exactly a flexible time, as seats fill up quickly and the airlines don't feel the need to keep those discounted rates out there any longer than necessary. By 8 p.m. Thursday, those sale fares are pulled and travelers who waited until the weekend to book are out of luck. "Most consumers buy their tickets inside of 30 days before departure, including leisure travelers," Seaney says. "It puts pressure on them during the summertime when seats start to sell out, and if they just shop a day earlier ... I like to tell people, at least for summertime, every day you wait adds $5 to your virtual ticket price."