They have to hire perm full time drivers off the inside part time employee list. I know guys who have been seasonally driving casual for 10 years and they will never be permanent because they dont want to work their way up inside part time first. The only way an outside hire casual can go perm full time is if there is no interest inside (driver list exhausted) or if management decides they want to hire like 6 inside drivers. They can hire outside for permanent driver but if they do they have to hire x inside people too. I think its 6 or 8 for every outside hire.
If you want to roll the dice and can sustain the pace with no guarantee that they would hire all those inside guys to get you then go for it, but drive safely. If you safely accelerate to the speed limit quickly you don't need to speed and if you safely walk at a brisk pace and work with a sense of urgency then you don't need to run.