All successful projects adhere to these five immutable principles during the lifecycle of the design, development, deployment, and operation. These principles are independent of any project or program domain or context in that domain. They are also independent of any project management method or product development method, including agile.
They ask five questions that must have credible answers that establish the foundation for success. Without credible answers to these 5 questions, the project has little hope of success.
So if you hear some unsubstantiated conjecture like ... decisions can be made without estimating ask how any or all of the 5 immutable principles can be met?