Some Lean Core Concepts are : Pulling, Kaizen – Continuous Improvement, Even flow, Limiting WIP, Reducing batch size , Team Work
As per me all the Lean concepts are applicable to Scrum. Let’s look how they are applied:
- Pulling – At the time of sprint planning we pull stories from the Product Backlog, and we pull what we can deliver inside the sprint boundary. The pull is done by the full team in mutual agreement. We often tell to pull less than more, because if we are left with time we can still pull again if needed, but a push is not good. Often new teams are told to plan very less to ensure that there is less push.
- Kaizen – The Sprint Retrospective is one event in the Scrum Guide where the team thinks about how things went and how to improve. This is not the only place to improve, in the daily scrum also the team see’s their progress and how it is going and often seeks new ways to improve from where it is. For example, if a person has an unplanned leave the team sees how it can rally to meet the team goal. Kaizen is a very essential core element of Scrum I feel.
- Even Flow – Every n week (2 weeks for some teams), the team pulls work of x story points and do that. Teams take less initially and grow more to find their average velocity. With time the maturity increase, and velocity might or might not increase. But the team keeps sprinting, there is no hardening/Sprint 0 as Scrum/Agile believes in Quality delivery so while sprinting they keep burning story points continuously.
- Limiting WIP – It can be done by limiting # of user stories ongoing at any time in a sprint to 2, which “forces” team to collaborate, and focus on completion. It is quite powerful.
- Reducing Batch size – When a new scrum team starts, I’ve seen team say let’s take sprint of 4 weeks and initially I don’t say no. But while time passes, we see how to reduce the size of the sprint to 2 weeks. The main reason of reducing boundary is ensure that the team can Dev/Qa/Validate all in a short span and they can really improve/inspect for that short time. The shorter the duration the easier it is to see failure too.
- Team Work – This is a very much needed in Scrum. The team rallies towards the sprint goal together, the Scrum Team is important to have good team work rhythm to ensure that they rally with each other to reach the desired goal. Apart from this the team members constantly help with scrum roles, like PO defines initial requirements, the Dev/QA confirms the requirement, then the Dev finishes coding, QA does validation, in all this work a lot of team work is needed for smooth transfer and create less waste.