Which part. Except the presentation, there's no prep required. It's all about what you know and what you have done in your career. No Leetcode, no algorithms, no bs questions.
Presentation sounds really vague to me, it could mean anything from 1-2 hours of prep or a day or two of intense preparation to make a good presentation.
Also number 1 (writing simple API matching a spec) - this doesn't require prep if it's using language that I am using currently / have been using in my daily job for a long time.
But I have found often been required to write code in languages that are on my CV but I haven't used them in 5+ years.
Also talking about past failures, career history. I can barely remember in detail 2-3 years so I would need to spend a little time to just be prepared about a random very specific question about a project I worked on 5 years ago that might come up during interview because it would silly if I didn't remember (which I wouldn't if you ask me randomly about something I did 5 years ago).
Small things like these add up, obviously the more you want to get a certain job the more time you would spend preparing, it's only natural. If you are only looking around you might just wing it since you don't care much.
I am not criticising your system, it seems pretty sensible actually btw.
