From a company’s perspective, sharing ownership increases the bus factor to more than one. The quirky term refers to the number of key people who can be incapacitated (for example, by getting hit by a bus) before the rest of the team is no longer able to keep the project going. A bus factor of one means that if any member of the team gets sick, goes on vacation, or leaves the company, the rest of the team suffers.

Moreover, interest payments on some technical code debt is higher than others. The more frequently a part of the codebase is read, invoked, and modified, the higher the interest payments for any technical debt in that code. Code that’s peripheral to a product or that rarely gets read and modified doesn’t affect overall development speed as much, even if it’s laden with technical debt.

He told us that one of the most valuable lessons he learned at Twitter was the importance of instrumenting everything. “For the first two years of Twitter’s life, we were flying blind,” Dorsey explained. “We had no idea what was going on with the network. We had no idea what was going on with the system, with how people were using it … We were going down all the time because of it, because we could not see what was happening.”