Agile Estimating and Planning (Robert C. Martin Series)

by Mike Cohn

Plan features of the right size. Functionality that will be added in the near future (within the next few iterations) should be decomposed into relatively small user stories—typically, items that will take one or two days up to no more than ten days. We are best at estimating work that is all within one order of magnitude in size. Working with user stories that fall within these ranges will provide the best combination of effort and accuracy. It will also provide stories that are small enough to be completed during one iteration for most teams. Of course, working with small user stories can become quite an effort on longer projects. To balance this, if you are creating a release plan that will look more than two or three months into the future, either write some larger stories (called epics) or estimate the more distant work at the theme level to avoid decomposing large stories into small ones too far in advance.