We're no greater fans of over-planning than we are of analysis-paralysis. However, we've seen far more firms (great and small) suffering from under-planning with bad planning as often the culprit as lack of planning than over-planning.
Scottish blessing: "No time for planning," "planning's too time consuming," or, "planning's too difficult” are not answers. They are pre-fact admissions of failure (refusal?) to lead.