Is working 18-19 hours a day the norm in FAANG+?

I would echo what Alex said. This differs from team to team. Keep in mind that if your friend is working ~135 hours per week, then their pay is not actually that great when considered on a per-hour basis.

I think what your friend is describing is nowhere near the industry average. Beyond what Alex wrote, I want to say that I find people love looking very busy, because they conflate busyness with importance or impact. They are not the same. For this type of role, working a lot is possible for some people, but most people would likely burn out doing challenging work for many hours and not actually sustain the high level of effort required. There is research on this (see Cal Newport's Deep Work, which covers how few people can do more than 4 hours of deep work a day). They are also more likely to make mistakes, which they then have to spend time fixing later. So while it's likely your friend is working significantly more than average, I would take everything anyone says with a grain of salt, especially if they are saying they barely sleep or eat and do nothing but work.

My recommendation would be to network with other engineers, learn about different companies' cultures, and get a sense of the day-to-day. Few things people are working are urgent and critical to the world to get done ASAP. It's normal to have the occasional crunch where you need to focus and get something out quickly. It's not normal for it to be the norm. If that's the case, the team needs to hire more people. So I wouldn't worry about this, and I'd get exposure to the perspectives of other engineers. I'd also talk to my friend about whether they might want to look at other teams/roles, but that's just me.

Definitely not expected or common to work 18 hours/day. As in, I've literally never heard of any team that does this.

Maybe it's for one night because an engineer was deep in a flow state, or perhaps one day during crunch time. But any kind of expectation for 18 hours/day would be ludicrous.

Okay, so the work-life balance of FAANG engineers is generally below industry average but it isn't that bad. 18-19 hour days literally means that you only have 5-6 hours just for sleep, let alone eating, bathing, and using the restroom... Tell your friend to leave their team ASAP. It doesn't matter how much you get paid, that experience can't possibly be worth it.

Is this level of commitment expected from engineers who are working on exceptionally valuable features or components within the company?

In general, FAANG expects you to be quite committed to your work, both in terms of putting the hours (relatively easy to do) and having high intensity of work (harder to do, more around shipping very high-quality of work). The latter is what trips up most engineers.

If you want to learn more about life at FAANG, check these out:

• "Typical Day of Average FAANG Software Engineer?"
• "How does Stack Ranking work (at FAANG) and how can I be proactive at a base level?"
• [Masterclass] Should You Work At FAANG? - What Big Tech Is Like For Software Engineers

My friend mentioned that their team is composed of individuals with high IQs but low EQs.

I've also seen this happen quite a bit, especially at the Big Tech companies with more LeetCode-heavy interviews (Google is the most notorious for this). However, the low EQs is more applicable at L3 and the lower end of L4 where your job (and interview) are mostly coding. Once you get to L5/L6, engineer EQ shoots up drastically as you need those more fundamental skills to perform at these levels. We talk more about this here:

• "What are software engineering fundamentals?"
• "What's the difference between a low performer software engineer and a high performer?"