tl;dr don’t ever be underprepared for the written assessment as the responses could be the only thing marked
Speaking from personal experience this year (altho I somewhat think that this only applies to the current year due to COVID), the ‘interview’ section, which was actually called a ‘faculty discussion’, is nowhere near an actual interview.
(Disclaimer: There could be changes in upcoming years, I cannot guarantee :3)
Our interviewer explicitly told us that this discussion would “not be marked or anything like that” and was just a “chat”. Although can’t deny that she seemed to be constantly writing things down, I highly suspect on the importance / necessity of the interview. The admission staff actually only had one afternoon to assess roughly 50 written responses (as they had to call for offers / rejections on the day), there should not be any time to go back to the interview recordings and check on each candidate’s performance.
So it was most likely that everything was based on the written assesssment!! My Google doc was very unresponsive when I was typing so I panicked for quite a bit, and didn’t even get to finish a question as it was quite time pressured :/