When traversing error chains in Rust, prefer using the `chain()` iterator method over manual source traversal with while loops. The `chain()` method provides a more idiomatic and readable approach to walking through error chains, eliminating the need for manual loop management and making the code more concise. Instead of manually iterating through error sources: ```rust let mut source = error.source(); while let Some(err) = source { if let Some(rl) = err.downcast_ref::() { return rl.retry_after; } source = err.source(); } ``` Use the iterator-based approach: ```rust error .chain() .find_map(|e| e.downcast_ref::()) .and_then(|rl| rl.retry_after) ``` This pattern works well with other iterator methods like `any()`, `find()`, and `filter_map()` to create more expressive and maintainable error handling code.