I applied to a new grad production engineering job at Facebook recently.
I probably did about 80 leetcode puzzles, let's just assume that is 1 hour per puzzle. So 80 hours of leetcode puzzles.
In addition, 10 hours were spent reviewing my networking trivia (focused on layer 2/3/4 and HTTP).
The PE recruiter at the company also provided a study guide packet. I elected to sink about 10-20 hours into studying the Linux troubleshooting and finding some common questions off of Glassdoor to understand the type of things they will be asking.
Finally I tried to review some system design stuff (but as a juniour in this industry didn't really know how) Just followed some study guides from the system-design-primer on Github. Probably 5 hours dedicated to this.
Let's just round it to about 100 hours of prep in about a month and a half. While juggling a full time job as a devops engineer.
Afterwards I was rejected :)
Ultimately I wasn't surprised I was rejected. I was under the impression that I needed to pass all 7 of the interviews in order to get an offer (2 phone screens, 5 on site.) I know for sure I failed the system design interview question HARD. Like irredeemably hard. Regardless of my performances in my other interviews, I know I definitely did a good job in my network and OS interviews but it doesn't matter.
I do wish that companies would provide a feedback system. I would love to know where they thought I was weak so that I can improve upon that later. But there is nothing beyond "we decided to pursue other candidates."
Here's the crazy thing, though. It isn't even a question in my mind that I should try again if another FAANG recruiter reaches out to me. I will sink another 200 hours if necessary to pass their interviews because of what it represents to achieve getting hired at such a firm. There's prestige, salary, and quality of life that just can't be matched by any other tech companies.