I once gave a detailed estimate of a project I thought would take 2-6 months. I called out the major blockers, explained the highest variability parts of the project, and made suggestions about how we could reduce variability.
Rather than address any of the points I made, the managers focused on nailing me down to a single estimate. Presumably they had to sell it as a quarter-long project.
I sat in the office of the engineering manager, and explained that any single estimate would be a lie. He told me that it wasn't a lie, it's just my best guess. I said my best guess is 2-6 months. He asked for 3 months. I said he can use whatever he wants, but my estimate is the same. I think they ended up using 3 months.
The ordeal complete drained my energy and the project went no where. My future estimates went through the roof and they eventually stopped asking. Now projects don't have any believable plans.