Although our flight planning software is reasonably sophisticated, the schedules/slots/stands take priority and we seem to fly at 0 when we're going to be too early and 100 when we might be on time or late. There was a period when we were planned at .85/320 (.87/330 Mmo/Vmo) down to South America to try and avoid having an extra crew member... didn't work very well through the ITCZ.
