For many investors, portfolio design seems straightforward: Simply choose the options with the highest potential returns. But for advisors serving clients with a wide range of risk tolerances, that mindset can quickly fall apart. For those who can't stomach sharp market swings, the "best" strategy on paper isn't always the right one in practice. That was the case that Zachary Rayfield, head of goals-based investing research in Vanguard's Investment Strategy Group, made during a session on glide paths at t ...