Silent process changes. A new product added without pricing rules, a discount approved outside the flow, a billing term the contract model doesn't represent — each one is small, and together they detach the system from how the company actually sells within two quarters.
The defence is a maintenance cadence tied to events (new product, new motion, new segment) as well as a clock. Build the field guide during the project — the full map of everything the quote button touches, what it changes now and what it changes later — so the next person can trace a break.
Every claim above comes from work LeanScale published. These are the sources.