What other sites are you looking at? I don't actually know that I'd recommend any puzzle sites to a new programmer. The ones I know of are for fun, not for improving your software dev skills.
But yeah, as a good programmer with a job at a large company, you _definitely_ don't need to do 100 PE problems, and any company asking for that (for general software dev role) has lost their mind.
Add to that, FAANG interview processes are mostly risk avoidant. They are more aimed at avoiding hiring bad candidates, than avoiding ignoring good ones. It is very often possible for a weak candidate to bullshit their way through interviews etc. Solving PE problems is harder to fake, at least without faking on purpose (by reading up on spoilers).
Also (and this includes Amazon) I've never had anyone on a loop/hiring manager tell me how to prep for an interview. That has entirely been the recruiter.
As someone with a math background, that was the only problem in the first 100 that I didn't find pretty straightforward.
Or meet fellow devs at meetups and get into open source.
Or meet people at a local hacker space.
Basically, developing requires people to inject interesting projects and perspectives at you.
Yes. Coding requires social skills. I'm not taking that back.
I expect you to tell me you're well versed in both, but don't expect me to believe you.