When things get complicated enough, you have to plan them in advance or they fail. You need blueprints and logistics before you can build a skyscraper. On a personal level, good plans improve our chances of success at anything we can make a plan for.

One trouble with plans is that once you've made them they're sticky. What kind of life to lead, what to study, when to marry - we inherit plans about these things.from the past and we don't always rethink them when appropriate.