But, like cooking, once you have the ingredients in place, it’s important to know how long to keep them on the stove. Time-boxed sprints are an essential part of Scrum, yet estimating how long a task will take can be problematic.

“Sizing is one of the bigger learning curves,” said Pegasystems’ Vidoni. “Our approach to estimation was to take a set of baseline stories of various complexities and to size new tasks to that reference point.”

Pegasystems has merged business processes with the development process, which Vidoni said provides the benefit of “really assessing what our business priorities are and not over-commit. We’re able to balance our tactical needs with the more strategic business needs.”

TypeMock’s Lopian agreed that project estimation was an early problem. Scrum advises that sprints take no longer than four weeks. At first, he said, “you don’t know how to estimate how long a task will be. It could take half the time you allot for it, or it could be three times as long.”

Trial and error got them down from four-week iterations. “We went to one week about a year ago, but the development team didn’t feel they could deliver value in that time, so we went back to two weeks. Now we’re more mature, and we’re back to one week.”

ThoughtWorks’ Humble took it even one step further, with the advocacy of what the company is calling continuous delivery. “It’s all about keeping software production-ready. Every four weeks isn’t enough. Continuous delivery means having software production-ready all the time,” he said.

Yet Scrum doesn’t prescribe any technical behaviors for achieving agile success, and that’s either a flaw or a compliment, depending on point of view.

“Scrum talks a lot about process and management of a project, but speaks very little about the engineering side,” said Excella’s Cheng. “XP talks more about that, with continuous integration, test-driven development and pair programming.”

To address this, Cheng pointed out that the Scrum Alliance is offering Certified Scrum Developer classes. “They’re trying to penetrate that area more,” he said.