production systems need slack

In The Goal, Eliyahu Goldratt introduces the Theory of Constraints as a way to think about production. One of the key insights is that the entire system can only move as fast as its slowest points. The heroes of the story spend a considerable amount of time trying to identify and then manage the flow of work that’s arriving at the bottlenecks.

When managers focus on the local maxima, its easy to miss the health of the system overall. When we try to maximize each point in the system, we create backlogs. If instead, we allow for slack, we will create a smooth production process. Slack is not a dirty word, though it can sometimes require a bit of selling to see why this is.

While we still have plants like those described in The Goal, a growing portion of production is happening in plants that look nothing like the old ones. The new generation is full of developers trying to churn out new software. While the aesthetics have changed, the rules haven’t. It’s just rare that anyone actually talks about software development as a production process with bottlenecks. Maybe if we did, we’d recognize that there’s need slack here too - even better, that slack can be a sign of health.