Google is calling me again for application design interview

I had my phone google onsite for application engineer position 1.5 weeks ago. HC reviewed my packet yesterday and they said they had positive feedback on 2 coding and 1 system integration interviews but did not get enough signal on application design interview. Has this happened to anyone before? I think I did not manage my time and did not have time to go into the details of application design( stayed in the top level). Could you post your experience with application design interview in google and how did you manage to dive deep into details within 45 minutes? Thanks