Hey - My name is Blake Ross and I'm a director of product at Facebook. Your statement is wrong. Facebook pushes code every day of the week, and our big weekly push is on Tuesday.
They push changes daily, and if anything, according to the video, they say they stay away from major pushes on Friday because weekend traffic is significantly lower and some problems may not manifest under the reduced load before it hits the fan on Monday.
From the guidelines: Be civil. Don't say things you wouldn't say in a face to face conversation.