Note: This post is about slack - the concept, not the collaboration platform with the same name.
Check these pictures.
The situation in the first picture doesn't have room for a new vehicle in the traffic stream. The time to reach the destination is unpredictable for most of the vehicles on the road. The road has already reached its capacity.
Look at the situation in the 2nd picture. The road has room for new vehicles entering the traffic stream. Also, this situation leads to a better possibility of vehicles timely reaching their destinations.
The gap between the running vehicles assures that the traffic is running at an optimized speed.
In these examples, the roads are the "systems", and the vehicles, the traffic, are the "doers". The gap between the running vehicle is the "Slack". This slack is important to a smoothly-flowing, efficient system.
Slack and Kanban
"Slack" is not regarded respectfully by many. But the slack we are talking about here is the slack in the system, which plays a vital role in keeping the systems healthy and improving the quality of work with every passing day.
Slack is a vital outcome of implementing the Kanban methodology right.
Kanban prescribes limiting the Work in Progress (WIP). The number of work items (stories, maybe) in each state in the workflow is purposely limited to eliminate multi-tasking. Simply, we don't accept a new work item in the state when we reach the defined WIP limit. Our hands are full.
Implementation of the WIP limit goes with the "Stop starting, start finishing" principle.
We all focus on the small stack of work at a time, get it done, and then bring a new work item in progress.
Do the right thing.
If you are done with your part, and the team is at the WIP limit, should you start a new work next in the queue? The Kanban answer is "No".
Don't start a new work. You got slack time.
Slack time can easily be misinterpreted as "idle time", but if we use it wisely, it will exhibit the highest advantage of the slack in the system.
How can you contribute with the slack time in hand?
You can use the slack time in the best interest of your team.
Help the work-in-progress
In your slack time, assist your team with the ongoing work. Help your team with clearing bottlenecks, or assist in communicating with other teams. There are several ways to contribute. Thanks, mate!
With a constant focus on delivering the stories in hand, and building the new features, the working day is not designed to take care of housekeeping activities like maintenance, refactoring of codes, or documentation. The slack time can be used towards these activities, which, in the long-term, will prove much beneficial to the team and organization. Cool, you fixed a few bugs even before they bother.
You may have ideas to improve your product, do things differently, or fix the bad architecture in your way, but you don't get time for trying that out. Utilize the slack time. You are adding a lot of value. Kudos!
You can refine the backlog in the slack time. Look at the next items in queue or the overall backlog (Look. Don't start working yet.). You may refine the work items for your team. Dig into the details to uncover potential questions, define the associated risks and dependencies, and/or start communication ahead of time. This way, the work item will be in a better shape to bring in next, and potentially be done more smoothly. "Thank you for your help, team-player!"
Learning & Development
Learning, development, and advancement are everyone's rights. Your learnings will ultimately benefit your team and organization. Utilize the slack times in reading, learning, and improving yourself for a more positive contribution to the team. "Hurray! You learned something new today!"
Slack time helps build the products more innovative and stable. It leads to time to think, to reflect, to fix, to manage, and to improve.
As it is said earlier, slack is important to a smoothly-flowing, efficient system. Slack also helps the team to respond to high-priority fly-in work with a lower degree of impact on the team's ongoing undertakings.
Designed Slack Time
We have seen, at many places, managers treating the slack time as a crime. Idle time for an individual is not accepted in the metrics.
Change loosely follows the law of gravity - it easily flows from top to bottom. If the lean-agile thinking leadership looks at slack as an opportunity and not a liability, the teams will thrive with innovations.
Leadership should understand that if the teams get time to think, experiment, relax, and reflect then you can expect innovations. A team can achieve 'continuous improvement' and 'effective response to change' by having slack in the system.
A working agreement can help teams eliminate any confusion about utilizing the slack time. If the team culture supports designed slack in the system, it leads to miraculous positive results and outstanding product quality. This leads to a happy team and ultimately reciprocates positivity in all directions.