During the 1920s, most proponents of scientific management, Frederick Taylor's approach for maximizing workers' productivity by intensively routinizing their jobs, antagonized the five-day workweek. Despite scientific managers conceded that decreasing hours might supply an incentive to workers, in practice they more often utilized pay differentials to encourage higher productivity. Those reformers who wanted to accept both scientific management and reduced hours had to make a greatly negative case, depicting the latter as an antidote to the rigors of the former. In conflict to the scientific managers, Henry Ford stated that shorter hours caused larger productivity and profits. However, few employers matched either Ford's vision or his particular interest in mass marketing a product—automobiles—that requested leisure for its use, and few unions succeeded in saving shorter hours through bargaining. At its 1928 convention, the American Federation of Labor (AFL) boasted of approachingly 165,000 members working five-day, 40-hour weeks. But even though this represented an raise of about 75,000 since 1926, about 70 percent of the entire came from five enormously well-organized building trades' unions.