Please note this company no longer exists!
We once had a new director assigned to IT. He was always asking questions about how many phone installs we could do in a day. During this point in history all phones required a wire back to the phone switch.
So that being said if the new install was into a location in the building that had wiring already previously installed and everything went smoothly one install every hour and a half would not be impossible.
However if there was not wiring in place and depending on the location there is no real way to set a time to complete the install.