NEW YORK ( TheStreet) - Black Friday is being measured by the success of retailers' early store openings. But these extended hours may not have been as lucrative as they appear. While earlier door busters did drive consumers into the stores, the gimmick failed to keep momentum building through the holiday weekend. "Black Friday may have come in with a roar, but it's going out with a whimper," says Marshal Cohen, chief industry analyst at NPD Group. "While record numbers took advantage of the door-buster deals and the early-hour deals, it appears that is where most of the action was." Those retailers like Wal-Mart ( WMT), Target ( TGT), Kohl's ( KSS), Best Buy ( BBY) and Macy's ( M) that moved their opening hours for Black Friday to midnight or earlier averaged a 24% boost in their conversions, according to the NPD Group. When compared to some stores that retained traditional early Black Friday morning openings, it appears that some may have lost as much as 8% in their conversion rates. There's no denying that shoppers turned out in droves and opened their wallets, setting precedent for the entire sector next year. The early openings served as a way to drive excitement and became a form of entertainment for the shipper. But come 10 a.m. there was a noticeable drop-off in traffic, says Howard Davidowitz, chairman of Davidowitz & Associates, a retail consulting and investment banking firm. "We didn't see a reboot," Davidowitz says. "For early openings to be successful you have to have the ability to reboot, and we just didn't see that same intensity continue later on Friday or the rest of the weekend. For this to work financially, the reboot had to be there." As a result, Davidowitz says if you look at the whole weekend together it wasn't that dynamic. "People are overly focused on how successful the early openings were, but that alone doesn't sustain you," he said. The lull that preceded early door-busters isn't unusual, but moving up these promotions cost retailers money and it's unclear if early openings were incremental to sales or just pulled sales forward, Goldman Sachs analyst Adrianne Shapira wrote in a research note on Monday. - Reported by Jeanine Poggi in New York. Follow TheStreet.com on Twitter and become a fan on Facebook.