The original definition of a retrospective, as presented by Norm Kerth, was a 3 day, offsite meeting. Since then, the Agile community has co-opted the practice and made it part of every iteration. In, Agile Retrospectives, we are given 5 phases to be covered, but no specific guidance on time. In her recent article, Refactoring Your Development Process with Retrospectives, Rachel Davies suggests that we have 30 minutes per week under review. In many teams I have seen first hand, they tend to minimize the time for retrospectives - even as little as 15 minutes. How long should a retrospective be to be effective?
Esther Derby and Diana Larson, in Agile Retrospectives, tell us that each retrospective should cover the following phases:
- Set the stage
- Gather data
- Generate insights
- Decide what to do
- Close retrospective
For each of these phases, they give several different practices that can be used to effectively perform the phase(such as Mad/Sad/Glad for gathering data). But perform all the phases, it takes over an hour (probably no less than two). If you are running one or two week iterations, are you willing to put in two hours for a retrospective at the end of every iteration?
In Rachel Davies' paper, she suggests 30 minutes for each week:
A rough guide to timings is a team need 30 minutes retrospective time per week under review so using this formula allow 2 hours for a monthly retrospective and a whole day for a retrospective of a several months work.
Does this imply that we should be having retrospectives no sooner than once a month? Or does that mean we should have 30 minute and hour long retrospectives for one week and two week iterations respectively? And how do we fit in all the phases in the shorter retrospectives?
Finally, many teams on the ground practice 15-30 minute retrospectives that don't have all the phases. They get little to no value out of this practice and end up dropping it or doing it out of habit.
So, with the varied advice and practice out there - what is the most effective? What are your experiences? Do you perform retrospectives regularly? If so, how long are they? Are they effective or wasteful?