Work in Progress (WIP) has been defined as work that has started but is not yet finished. Sometimes, it is also referred to as partially completed work. In agile development, WIP limits set the maximum amount of work that can exist in each status of a workflow.
There are multiple benefits of limiting your work in progress, but the most important one is that it will make it easier to identify inefficiency in a team's workflow.
“Limiting WIP is a simple, versatile tool, resulting in people examining their work, eliminating unnecessary tasks, and finishing valuable products faster”. ─Jim Benson
Benefits of limiting WIP:
Work on higher priority tasks first
Build trust with those audiences by putting things out regularly
Identify bottlenecks in the team’s workflow
Collaborate between teams to complete features
Complete any integration needed for each story
Whether you are using Kanban or Scrum, agile and lean principles focus on getting things done in small batches and WIP limits reduce the amount of work "nearly done", by forcing the team to focus on a smaller set of tasks.
Kanban uses cards, columns, and improvement to help all teams get the right amount of work done. Kanban is based on a continuous workflow structure. If there is a lack of flow (because of too many work items in progress, blockers, or other impediments) the Kanban board immediately draws attention to the associated columns.
Some scrum boards do indicate WIP limits, but these are often not strictly observed since everyone on the team is focused on getting the work done before the Sprint is over (usually 2 weeks). However, scrum teams can introduce concepts into their Sprint (Scrumban) and set WIP limits for the team.
Here is a great video from Atlassian about Kanban WIP limits.
How do you calculate work in progress limits?
There is no right answer. The truth is, you will need to experiment and find the WIP limit that is low enough to identify bottlenecks and promote a good flow for your team. Every group is different and you will need to adapt every process based on your team situation and experience. However, there are 4 steps in Kanban that can guide you in the process:
Map your value stream
Calculate the efficiency of your board (flow efficiency is the ratio between your active time and total time
Identify the number of total tasks on the board related to the size of your team
Set WIP limits for each column
Stop trying to do everything at once. Instead learn how to say no, rethink your priorities and talk with your manager or leadership about setting clear expectations about your workflow. A good leader needs to become a team protector, keeping them from splitting their focus across too many projects. Adopting agile means creating, exploring, failing, developing, and continuously improving. Having a limit on the amount that can be handled for the team is a key to continuous improvement and efficiency.