Why are my React components re-rendering excessively despite `useMemo` and `useCallback`?

I'm optimizing a complex UI and have meticulously applied `useMemo` to expensive computations and `useCallback` to event handlers, yet profiling shows persistent, unnecessary re-renders. I suspect there's a subtle dependency I'm overlooking or a fundamental misunderstanding of React's memoization nuances in this context. What common anti-patterns or debugging steps am I likely missing here?