They hay we buy and have hauled in are all combinations of the above.  Some have net wrap, some have twine (usually solar degradable or plastic), and some even have sisal twine.  Some are stacked "cylindrically," and others are stacked 90 degrees differently.  Either way, I can always get them apart without using a tractor or without taking off the spinners from my Hydra-Bed.  Possibly other bale beds with bigger spinners would not work as well as does a Hydra-Bed.