The tumblr deploy schedule. Blue vertical lines are deploys, green stacked graphs are requests per second, annotations are my own.
People start deploying just after 10am (not surprising, most folks come in around 10) and keep deploying code until lunch time. Lunch time is a very social thing here, so most folks head out for a bit. After lunch, people are heads down until snack time. Snack time does not really exist. Code pushes resume again after snack time and go until dinner, just after 7pm. After that, last minute bug fixes until just after 8pm. Then sleep.
These opinions are my own. I don’t actually think most tumblr employees go to bed at 8:00pm. There also is not any officially scheduled snack time, although this would be cool.