Of course things don’t always work that way. Most problems are dynamic: in the time that it takes you to assemble the facts and decide what to do, the parameters have often changed. The competition makes a new move, the kids grow up, it rains, there is a re-org, commodity prices rise, there is a thunderstorm.
And so any strategy you come up with must itself be dynamic. You need to be ready to adapt and adjust.
That’s why detailed project plans fail more often than they succeed except for the most mundane, repeatable tasks - the problem is not with the execution of those plans, the problem is with the plans themselves - in their static nature.So how does one deal with that ? Its really not that hard once you make yourself aware of it. You just have to explicitly factor in contingencies, remain flexible, and have regular course-corrections as part of the planning itself.