The only difference between Scrum and Kanban in terms of work priority is that with Kanban you prioritize the backlog and take the next thing off the top. With

The only difference between Scrum and Kanban in terms of work priority is that with Kanban you prioritize the backlog and take the next thing off the top. With Scrum you prioritize the backlog and try to forecast the volume of items from the top of that backlog that you'll be able to work into the sprint based on past velocity. You're not wrong about the arbitrary estimate. Prioritization is a function of the company and/or product team. If you need to do something in the sprint that you didn't know at the start of the plan, yes there are definitely scrum teams that would try to stop you because they are too strict with their process. Don't get me wrong here, this perception is a standard antipattern that you see in scrum shops. I've only seen a scrum team once in my career that was actually effective and I'm a huge Kanban advocate because of it. https://news.ycombinator.com/item?id=17154355 https://news.ycombinator.com/item?id=17154355 But prioritization still happens at a higher level than the team itself. It has to because it defines the direction of the company. Most importantly, deciding what you're NOT working on so you can focus on what matters.