40 hours seems low to me if one wants to enter FAANG. Even if you’re familiar with the process and have prepped before. I’d expect 100 hours minimum for most candidates. Only exception would be those who interview regularly, do competitive programming regularly, and those who have to do algorithmic work regularly.

Most people I know spend nights and weekends prepping for at least a month to a quarter.

I did it over 4 weeks. I have two kids, so I spent about 1-2 hours per day. I usually did some reading or a couple leetcode problems in the morning before starting work, and a couple in the evening. Honestly, once you do about 20-30 problems, they start to feel the same. I found that if I treated each problem like an interview and slowly walked through a solution (versus just diving into code and mashing Compile over and over until I get it), the problem ends up being easier.