Does a Shorter Sprint Deliver More? – Explained with Little’s Law
Using the principle of Little's law, we take a look at sprint duration and how it can affect the time to market of a product.
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Agile development methodology suggests sprints suld be time boxed between 1 week and 4 weeks. Most agile leaders recommend smaller sprints and find that teams deliver more value with smaller sprint. While trying to understand the reason behind the benefit of small sprint, I found that Little’s law helps us to identify the reason.
Little’s Law states:
Cycle Time = Work in Progress (WIP) / Throughput
Let me define each term from agile perspective:
- Cycle Time: Total elapsed time to move story from TO-DO state to DONE state.
- Work In Progress (WIP): Total number of stories in sprint backlog
- Throughput: Tasks completed by developers in unit time.
We can easily assume that the faster we move stories from a TO-DO state to a DONE state, stories will be completed faster, and consequently more values will be delivered to end users. Moving stories faster from TO-DO state to DONE state requires us to reduce the cycle time of stories.
As per above law, we need to either increase throughput or reduce WIP (sprint backlog) to reduce cycle time. Now in the real world, increasing throughput of developers in a short span of time is not an easy task. We may have to hire more experienced developers, provide more training to teams, teams may have to stretch, and lot of other activities need to be done to reduce waste and improve throughput.
Another option is to reduce WIP (sprint backlog). Sprint backlog is created based on estimation of stories and the capacity of the team. We should not change estimation of stories and for quality deliverables we must get estimation from team. Consequently, reducing capacity of team is the only option to reduce cycle time. Now if we want to reduce capacity of team, we are left with only one option: decreasing the duration of the sprint. That means a shorter sprint is the only way to reduce the WIP items, which will cut cycle time and help us to move stories faster from a TO-DO state to a DONE state.
We have seen that shorter sprint lowers the cycle time and also helps us to close stories faster. Shorter sprints help teams to commit less stories, which means that the team has fewer items to focus, which leads to less noise in the development cycle, less task switching, fewer dependencies and fewer unnecessary communications across teams and shores.
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