- The team's ability to become predictable within the sprint duration.
- The Product Owner's ability to plan and to commit to the unknown of not changing the plan for the sprint's duration.
- The frequency of needed feedback on the direction the team is making toward the release goal.
- The ability of the team to create their sustainable pace.
Many team's I've worked with have trouble defining their sustainable pace. I've argued that this pace that allows the team to deliver both working software that is potentially shippable each sprint and to have high quality deliverables along with team learning is quite a bit below the teams typical sprint velocity.
When teams are under extreme pressure to deliver they typically forget one of the 7 habits of effective people - to sharpen the saw. So why not build this habit into the structure of your team's cadence? Instead of a two week sprint (10 work days) try the 13+2 model. Thirteen work days followed by 2 days of slack (read the book: Slack: Getting Past Burnout, Busywork and the Myth of Total Efficiency).
This three week sprint length will add in 13% slack to your sprint in a tempo that is easily predictable for the team members. You might find that the team members start using this 2 day slack time for things like doctor visits and Fed-Ex days.
Slack and the Manager's Role in Scrum by Andrew Fuqua
21 Tips on Choosing a Sprint Length by Mishkin Berteig
Hat tip to my friend Caleb Jenkins for the idea - I told him he better patent the idea, or I would steal it.