I'll be sharing notes from my system design prep - I'm currently going through Hello Interview resources.

My takeaways from '5 Keys to Staff-Level System Design Interviews' by Stefan Mai that I think apply at the senior level too:

#1. Make decisions in two steps:

a) Be thorough: offer a menu of options based on possible trade-offs.
b) Be action-oriented: actually pick one.

#2. Casually bring up previous experience.

If you are asked to design a system with high QPS, and you've worked with such a system in the past, mention it in and draw parallels/learned lessons. At higher levels, you are paid for your experience.

#3. Direct the discussion to the hard/interesting parts

Even if you can do the easy parts well, it does not help you stand out as much.

- If a part of the system doesn't need to scale, suggest the simplest approach (with justification) and move on.

- If a part of the system can be solved with a standard approach ("this is just a CRUD API"), say that and ask the interviewer if they want you to expand.

Article: www.hellointerview.com/blog/staff-level-system-design