Comment by RafiZ

Founder of Pramp.com here. Coding and interviewing are orthogonal skills. Being good at the former doesn't mean you're good at the latter. My recommendation to you is to challenge your own assumptions about your interviewing skills. Do you know for sure that you can do a credible job at system design? Is the process you use when tackling a problem aligns with interviewers' expectations? How are your communication skills? The point is that practicing coding interviews with other engineers will allow you to get unbiased feedback about many of the aspects above.