when should you think about using a circuit breaker pattern

hey everyone, i've been working on distributed systems lately and the topic of failure handling keeps coming up. we've had a few cascading failures where one service going down caused a chain reaction. i've read about the circuit breaker pattern and how it can prevent this by stopping requests to unhealthy services. but when is the right time to introduce this complexity? is it only for microservices, or can it be useful even in a more tightly coupled architecture? what are your experiences and when did you find it most valuable?