Usually that problem is dealt with combination of: * Automation. * Ability to change other people's code safely, possibly gated by code review approval. Cultu

Usually that problem is dealt with combination of: * Automation. * Ability to change other people's code safely, possibly gated by code review approval. Cultural and technical (e.g. unit tests must exist and be maintained) barriers may apply. * Making incremental changes that are backward compatible (at least until you migrated all clients so you can cleanup later) I recommend this talk https://youtu.be/tISy7EJQPzI https://youtu.be/tISy7EJQPzI (even if the scope is broader than your question) (ex-googler)