While the practice of creating excess capacity in the delivery process is well-known in the product management community, we still see far too many teams planning for full utilization of team members. Reserving some capacity during sprint planning generally leads to better predictability and better quality; it promotes team resilience to unexpected events like illnesses, production issues, unexpected product requests and tech debt, while also allowing productive activities like team building and ideation that can lead to product innovation. Running at less than full utilization means teams can be more thoughtful about the robustness of the resulting software and pay closer attention to the right observability signals. Our experience is that a fully utilized team leads to a collapse in throughput as well, just as a fully utilized highway creates slow and demoralizing traffic. For example, when one of our teams had unpredictable support issues, they saw a 25% increase in throughput and a 50% decrease in cycle time volatility by planning feature velocity based on only two of the three developer pairs' capacities.
