By Markus Sprunck; Revision: 1.1; Status: final; Last Content Change: Aug 16, 2012;
This article describes how to reduce waste due to interruptions in software development teams.
One of the key targets of Lean IT is the reduction of waste. Looking in a software development team you see always a lot of waste, e.g. poor quality, inconsistent documentation, too much manual tasks, communication leaks, missing technical know-how, interruptions and/or context switches during work.
Today I'd like to focus on interruptions or unwanted context switches during work. Just observe for two hours the work of a developer in your team and you will be distressed about the small percentage of productive time. My personal impression is that the number of interruptions are quite independent of the development approach (agile or waterfall). The key lever is the awareness in the organisation, team members and the working environment.
Each interruption or unwanted context switch can costs time or creates errors. For example a developer is highly concentrated in a debugging task to find the root cause of a problem. A peer comes and asks a "short question". The developer answers and needs then some minutes to find back in the task. This setting-up time is pure waste.
Last year, I asked myself how to measure and reduce these unwanted context switches. During the weekend my children played with glass-nuggets (germ. Muggelsteine) and that inspired me, to count the context switches with these glass-nuggets (see figure 1).
In the evening each one, had just to put his/her gass-nuggets in a big box. In the next morning I counted them and added a point in a diagram at the team's whiteboard.
It was a clear success, because: