I've just landed a job at a FAANG company. Some random subjective comments based on my experience:
- it was hard work
- there was no way I could have passed these interviews without all the work.
- my past experience and education barely helped me for the interview
- it's not enough to be able to solve the problems, you need to be able to solve them on the spot, without much thinking, in an interview context
- I passed system design quite easily, even though I have little real-life experience with these systems. It would have been easy for interviewer to catch me off guard on real-life technical details, but they didn't care
- these companies (FB and Google) gave me a chance (even several ones), even though my resume is slightly atypical, and I'm on the older side (mid forties)
- Recruiters and interviewers were friendly and respectful. Overall they gave me a very good impression of these companies
- The whole process is very random
- I did learn some things while practicing. Not the best use of my time, but not totally lost either
- Algorithmic questions were harder at Google compared to Facebook
- The whole process was more fluid at FB (team-matching at google took forever, I was even ghosted by a recruiter after she told me I passed).