This is the mindset of many companies, not just startups. Just maybe to a lesser degree. My company requires 7.5 hours of work per day (not counting lunch) or 9.5 as a manager. This is a fairly large company. You will never be promoted working close to the minimum even if you have good output/outcomes. It seems like you need to do 50 hours a week minimum to seem engaged and dedicated, and this increases the higher up you go. I was on a product that had all the tech leads working 9 to 11 hours every weekday plus some time on the weekends. There was also an unspoken expectation that you would do some amount of work while on PTO.
