to minimize the maximum transportation time and to balance the time across vehicles.
However, sometimes when I set a number of vehicles it utilizes them all and if I set even more vehicles, it utilizes less number of vehicles than the number of vehicles which I set the first time.
For example, if I set 21 vehicles, it utilizes all of them and if I set 30 vehicles, it utilizes 20 vehicles. Is it a normal behavior and if it is? Why is this happening?
I suppose, in my example that even if I set 30 vehicles, it should be use 21 vehicles and not a vehicle less!