This isn't representative of my personal experience nor my peer/friend groups' in tech. Anecdata: of the ~5 senior engineer friends I have at large tech companies only one of them consistently works much more than 35 hours a week.
I was actually really heartened to see this article on HN because slow mornings have been life changing for me. Spending 3 quiet hours in the morning on my own pursuits has been wildly mood elevating. Plus, I usually use one of those hours to read about tech (although HN is banned from my morning hours). Five hours of study a week is easily ~240 hours of spaced repetition even if you miss a few weeks, and I would bet good money that it's more studying than the vast majority of my coworkers.
I was actually really heartened to see this article on HN because slow mornings have been life changing for me. Spending 3 quiet hours in the morning on my own pursuits has been wildly mood elevating. Plus, I usually use one of those hours to read about tech (although HN is banned from my morning hours). Five hours of study a week is easily ~240 hours of spaced repetition even if you miss a few weeks, and I would bet good money that it's more studying than the vast majority of my coworkers.
Balance is thriving in SF/SV from what I can see.