Definition:
One of the principles behind the Agile Manifesto speaks about “Sustainable Pace”
“Agile processes promote sustainable development. The sponsors, developers, and users should be able to maintain a constant pace indefinitely.”
Sustainable Pace is an essential part of Extreme Programming (XP), where Kent Beck suggests working no more than 40 hours a week, and never working overtime a s second week in a row. Working overtime sucks the spirit and motivation out of team. When team becomes tired and demoralised they will get less work done, no more, no matter how many hours are worked. Instead of pushing people to do more than humanly possible change the project scope or timing.
To set development pace, team should take seriously that they must deliver completed, tested, integrated, production ready software at the end of iteration. Even if it is last day of iteration it is better for the entire team to re-focus on stories which can be completed than keeping many stories incomplete. Building a sustainable pace, as you plan your releases and iterations keeps team away from getting into death march. The team should aim for a work pace that they should be able to sustain indefinitely.
Sustainable Pace is not about taking it easy and going slow, instead it’s just the opposite. It is investing energy wisely by setting your focus on priority items, delivering at regular intervals i.e every iteration and regain strength without overburdening as a continuous process.
Further Reading:
http://agilemanifesto.org/principles.html
http://www.extremeprogramming.org/rules/overtime.html
http://www.sustainablepace.net/what-is-sustainable-pace
https://ronjeffries.com/xprog/what-is-extreme-programming/#sustainable
http://www.inf.ed.ac.uk/teaching/courses/inf2c-se/Lectures/agileHO.pdf