I have been thinking that there is some personality left in the Zombies if their human cognitive functioning was high.
they return to familiar places because of this. The Arena may have been a refuge for either Randy or Ink/Roberts, or both!!


We don't KNOW how the numbered "little ones" are made/modified. Neither the means, nor by whom. To suggest that Randy or Ink/Roberts is behind it is speculation. (though I think they are somehow involved.)
We have heard some of them speak. (but do we know which ones?)
We know that they can recognize objects and places, but reading/comprehension is a stretch. (Randy walking with a particular bag does not suggest to me that he read the back and chose it, just that it was familiar.)

When Michael recognized Randy at the Tower, when Randy was walking off with Tanya, Randy was walking with some zombies that were burned. My thinking is that these regulars were from the Arena, since the arena had by then been destroyed by the Mallers/Eastern Bay Residents.
After the Arena was destroyed the zombies flocked to the hospital. If memories still serve the "smart ones" these locations may have had significance.
Randy may have been the point man for the Arena group. And Ink was holed up at the hospital/psychiatric ward. (The one Riley shot at had a "disfigured hand", and Burt shot Pin Stripe in the hand after he gained access at the Tower)