The roll off time is between the production of two units. It is usually defined by how long it takes for the unit to roll off the build pad. The time is not deterministic, some units have a tough time existing for the first few seconds and therefore delay production quite a bit.
While working on a pull request, inspired by this forum post I noticed that the roll of time only exists because the factory is forced to wait for the unit to finish the first command (that makes it leave the build site). But what if instead of waiting for the unit to leave the build area, we just wait a set amount of time and then just start building the next unit?
In short, do we really want to wait for the unit to leave the build site or should we make it deterministic and just start building after a second or two?