6pm it starts to slow down, by 6:30 half the office is heading out.
Some people would get there super early and leave early-ish.
Look, at the end of the day it's about getting shit done and COMMITTING CODE. That latter part is something a lot of people refuse to accept. It doesn't matter how smart you are or how much experience you have or whatever... if you're an IC, then deliver high-quality code (and a lot of it), and you'll have a great career.