It took Deb Still 28 years to reach the corner office. Not that the chief executive of Pulte Mortgage is complaining. “The culture that I’ve probably always worked in is a culture that’s rewarded hard work and competency and business results,” she says. “That’s what I’ve focused on.” Still is a good example of the progress women have made in the housing finance industry: She started out doing grunt work — processing loans —put in long hours, pitched in on extra projects, built her visibility and steadily moved up the ladder to become leader of the mortgage finance arm of Pulte Group Inc., one of the nation’s largest homebuilders.