I think you mean "plans are useless but planning is vital"

There is another saying in modeling and simulation: All models are wrong, some are useful.

As an Eng. Leader I use planning and estimates to communicate with other stakeholders.

One thing the majority of people fail at is giving variance when providing a forecast/estimate.

If someone asks me to get an quick estimate for developing something I'll give them a range with wide margin, around the avg time I think it will take. If they want to reduce that range, then I need info to understand the requirements better.

Problem has always been that what engineers provide as an ESTIMATE, business takes as a deadline. So, engineers: always add buffer to your estimate.