Principle 4: Level out the workload.
Scrum levels workload by having team members self-assign tasks from task boards based on the tasks’ complexity and their own schedules. In addition, the product owner works with the team to define the whole team’s workload, or production cycle, upfront—we call this cycle a “sprint.” Team members respond by prioritizing each of their own tasks to deliver the desired results.
“40 hours is the time we want to spend at work” … “We should ban over hours!” these have been some comments in a training last week. We all know that people who work long hours are not more productive. We all know that people who work long hours are not focused and we all know that people who work long hours do have a problem with their work life balance. (I am an example 😉 )
The TPS principle can be simply applied in any Scrum project, team, organization. People need to put as much work into their Sprint as they can do stress free.
It sounds counter intuitive but this makes people faster, creates more productivity, stops people from making errors.
All this is not new … it is very old knowledge in fact. So let us apply this.
 Scrum Delivers, Boris Gloger, Scrum Alliance Website
 The Toyota Way, Jeffrey K. Liker