A good plan executed right now is far better than a perfect plan executed next week.—General George S Patton, Jr., United States Army.
There's doing it right, and there's doing it perfectly. You want to focus on the former and not the latter. There’s a concept in the military known as “commander’s intent.” Basically the idea is to focus on the goals, the purpose of the operation, and key tasks to accomplish. In the old days, product leaders tried for perfection, anticipating all eventualities. That’s why it took so long to create a marketing plan or a product plan. Nowadays as we all try to be lean and agile, you’re better off making a rough plan and relying on your team members’ judgment. Give them goals. Provide them with stories about users and buyers, and let ‘em run.