Upcoming system design interview @Monzo

Interviewing for Senior Software Developer at Monzo. I'm prepping on classic problems like Top K Frequent Elements, Rate Limiting, etc. But I'm wondering: **how deep do they actually expect you to go?**

For example, if they ask a Top K problem, do they:
- Stop after you suggest a heap? ✓
- Push you to optimize further (distributed, caching)?
- Expect you to code it out?

Also curious: **breadth vs depth?** Can you get away with being stronger in one area (e.g., databases) or do you need to be solid everywhere?

Anyone who's interviewed there recently, what was your experience?

Thank you in advance