I like how Mike Tyson put it: "Everyone has a plan until they get punched in the mouth".
neither of these are alternate formulations of the op
its not so clear cut. they both tackle the "plans are useless" but the "planning is indispensable" is implicit as anything you do in response to a challenging situation is a plan
Or that plans are only useful when they fail and are adjusted.
The first time I read this I could not understand it. It makes a lot of sense now seeing how plan execution is where project management really happens.