LATE one Friday afternoon at a leading consulting firm, a last-minute request came in from a client. A female manager was the first to volunteer her time. She had already spent the entire day meeting with junior colleagues who were seeking career advice, even though they weren’t on her team. Earlier in the week, she had trained several new hires, helped a colleague improve a presentation and agreed to plan the office holiday party. When it came time for her review for partner, her clear track record as a team player combined with her excellent performance should have made her a shoo-in. Instead, her promotion was delayed for six months, and then a year.