A typical system design interview is - minutes. Here's how to pace yourself:
Minutes -: Clarify requirements. Ask questions. Don't assume.
Minutes -: Estimate scale. QPS, storage, bandwidth.
Minutes -: High-level design. Draw the architecture.
Minutes -: Focus on - components. Show depth.
Minutes -: Trade-offs, bottlenecks, future improvements.
Watch the clock. If you spend minutes on requirements, you've lost.