You can reframe estimation tasks to identifying where there's uncertainty, and what the PM should prioritize to ensure the project is successful. Your estimate

You can reframe estimation tasks to identifying where there's uncertainty, and what the PM should prioritize to ensure the project is successful. Your estimates are prioritization inputs and tasks for the PM to do, managing said PM. Gannt charts do this well, and you can apply rhetoric to your arguments by setting some tasks to be much much longer than others. The reader will see those items as the most important and influential for affecting the total time