(See also Stories and the Tedium of Iteration Planning Meetings.)
Doling stories out to individual developers not only makes for more boring iteration planning meetings, but it also impacts the system’s overall quality.
One of the most overlooked practices in software development today is review. If you don’t pair, then you really must find a way to consistently review work product. Unfortunately, most companies pay the cost of not doing this: code that is increasingly more difficult to maintain, and solutions that are questionable at best.
Insisting that a team finish a story every couple of days or fewer will often mean that two or more developers must collaborate on a story. In order to collaborate, they must agree on some part of the design and a plan to implement it. The developers will need to continue talking as the implementation progresses. That’s a good thing. Much of the resulting design won’t be one developer’s wonderfully clever or woefully inadequate brainchild.
Such collaboration brings a bunch of siloed developers one step closer to being a true team. Initially, velocity will decrease a bit: developers will have to learn how to talk to each other and coordinate things. Developers will learn more about other parts of the system, increasing their value to the project as well as their personal worth. It’s not quite as good as pairing, but it does go to the heart of agile.