A Small Difference in Developer Productivity Can Amplify Over Time

Small differences in the productivity of software developers on a team can easily magnify themselves over time.

On many software teams, one engineer seems significantly faster than the others. Now, in some cases, it’s because that engineer is cutting corners left and right. They get stuff done, but they cause damage. They’re a tactical tornado.

Let’s assume your fastest engineer isn’t that type. They put out good code. It’s possible that they’re not actually as fast as you think. It turns out that even a marginal advantage for one engineer can translate into significant speed differences.

Let’s imagine a simple team of two engineers, Amy and Bob. All things equal, Amy would be 10% as fast as Bob. And by all things equal, I mean they’d produce the same quality of code, Amy would just produce 10% more. This slight speed advantage could be because she’s naturally faster, or because she joined the team earlier and hence has more context on the code.

That 10% difference can actually translate to a pretty large difference in output. Initially, Amy produces 10% more code. Now Bob has to increase the time he spends doing code reviews of Amy’s code, and just generally keeping up with Amy’s changes so he has context and can make the changes he needs to make. Which means he has less time to write code, which frees up Amy to be even more effective, which increases her output yet again.

Over time, this is amplified. Amy is spending most of her time writing code. Bob is spending most of his reviewing and keeping up. Amy’s slight advantage turns into a much larger one. Other colleagues start to view her as the go-to person, and wonder why Bob is falling behind.

A good engineering manager or senior engineer can detect when that’s happening and try to correct the balance. But often the team kind of settles into a mode where Amy is assumed to be better and more productive and everything is funneled to her.

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