Granted I didn't ask if that was standard interview prep for them prior to interviewing, so this is partly my own biases filtering through, but I didn't get the sense that the seasoned 30-40 yold engineers were on leetcode for 6 months to pass interviews. I'm not saying none of them do that, but I found the Google interview process pretty standard fare for any place that has a similar quality bar.
I remember my interviews with Google & Facebook as a new grad & they felt far more grueling than as a senior engineer (that & 10 years ago they were still asking those brain teasers like find the voltage between two points of an infinite lattice circuit).
At this stage in my career, I've found the interview questions are all about how to design large pieces of software with the coding aspect being a smaller piece of the pie to make sure I'm not BS'ing.
Some people leetcode for ages to get lucky in interviews. But loads of people just interviewed and are highly skilled and qualified. I think I did a week of prep ahead of my interviews.
Some people also get lucky. Luck is a huge factor in FAANG interviews. I've seen people who are definitely no more intelligent or better at LC type problems than average Joe just get lucky with their interview loops - while others who have won competitions just get the inverse luck and don't get an offer.
