I really liked the sentiment behind this, and think that it probably has a lot of application beyond game design.
Focus on second-to-second play first. Nail it. Move on to minute-to-minute, then session-to-session, then day-to-day, then month-to-month (and so on). If your second-to-second play doesn’t work, nothing else matters. Along these lines, if your day-to-day fails, no one will care about month-to-month, either.
(via Applied Game Design)