This is how I am too. Unfortunately, my team isn't as stacked as it should be and I find myself working 10-12 hour days pretty often. For each deadline cycle, I usually try to have a day where I'm on from about 9-5 (also am guilty of walking away to run a quick errand or doing something around my condo), but then I jump back on around 9pm when no one else is on and stay on until 4/5am since I can knock more out. It's nice being on when everyone is going to sleep for the next work day, and the world is just quiet in general.