Wonderful article, read it like a blockbuster with a constants clicking in my brain. Every time I tried to impose some sort of sprints for myself and the team it always end in Friday superdense coding with a half task moving to the next sprint. Thank you for a great argumentation why precise estimation is a bullshit bingo, I tried to show to PM's that only a steepness of slope is important and managers can plan work without exact dev-hours, but without much success, your explanation is clear and easy to understand.