I don't quite get what you mean. Surely a temporary contract is ideal for a grad student intern, who doesn't have time to enter full-time employment?
As for flexibility of hours on interim contracts, it's nonexistent, because employers don't want to give that. They'll hire whoever just complies with their hours and usually not even allow for swaps.
I've even been on the other side of this. Allowing hour swaps leads to first the impression of preferential treatment, then actual preferential treatment (because "he's doing it"), then fights, then a total disaster.