Did you ever copy-paste builder methods across similar builders and just accept it?

This is especially painful when creating multi-stage fluent APIs — ones that only expose valid methods at each build step.

CRTP (Curiously Recurring Template Pattern) eliminates this entirely. It lets base classes return the concrete builder type instead of the abstract one.

The problem isn't your services. It's the assumption that processing time is deterministic.

• What if the system is slower today?
• What if the delay is too short... or unnecessarily long?

This is time-driven testing. It's fundamentally non-deterministic.