If anything, this shows how tightly the ships schedule is planned. The beancounters world.
Anyone who is connected with shipping knows that a plan is usually good for about 5 minutes. There are so many variables out of anyones control.
I'll bet though that the ship is always when and where it is suppose to be.
Like the ship that caught an abandoned anchor in her hull, in the Deleware River channel and caused a fuel spill-channels sometimes aren't exactly what is on a chart.