A friend of mine contacted me last week for advice. The “project management” had decided to adjust the length of the current sprint due to a number of ‘days being lost’. He wanted my thoughts on it. I found it curious at first, I can understand the point of view that you want a 10 day sprint and if a few days are lost you only get say 7. So why not add three more days in? Hard to argue against the logic (especially not knowing what lost means exactly). I wouldn’t have done it for a number of reasons.
Extending the sprint could lead to less reliable or predictable velocity, which in turn could screw with your release planning. Maybe, maybe not, perhaps it’ll iron out over time, that would make sense if you rarely changed the time-box. What if you did it regularly, constantly unstable iteration lengths would surely lead to velocity being less accurate or even pointless. Surely the point of having fixed time-boxes is how we track progress against the backlog? I’ve no problem with varying the sprint length, but changing it mid sprint? I just don’t like it, I don’t think teams like it and I don’t think you’ll have any reliable ability to estimate when stories could be delivered. End result: Planning is harder, teams feel disrupted
I like the idea of my teams feeling a sense of rhythm, establishing the Scrum ceremonies as the heartbeat of that rhythm. Established time-box lengths that we stick to regardless of ‘lost days’ (planned for or otherwise). They feel comfortable with them, estimating the amount of work that can be done is likely to be more accurate over time. A lack of rhythm can make scrum feel undisciplined and chaotic, a charge levelled at agile methods by many of it’s skeptics. End result: Disruption, poor estimation, feels chaotic.
In many ways this reason is possibly the most important. The sprint lengths really ought to be determined by the scrum team. After all, we are giving the responsibility of the planning & delivery of the product to them. If an organisation is serious about adopting Scrum or agile methods then allowing the team to choose the length of sprint that works best for them is vital. If the organisation decide the sprint lengths, this affects the feeling of being “empowered” within the team. Essentially you’re a back seat driver. End result: You giveth and you taketh away
This is the kicker for me, if you expand the amount of time available to complete a piece of work, you will expand the amount of work to fill it. Don’t ask me, ask Cyril Northcote Parkinson, expanding your time-box doesn’t mean you’ll get any more work than you’d have gotten originally. The remaining work will expand to fill the expanded time-box. End results: Nature abhors a vacuum.
You may disagree, but for me expanding your time-box is fruitless..
This isn’t football where you can add time on because Didier Drogba has been rolling around the floor for 5 minutes pretending he has an OWIE!