I've never even seen Gregor patrolling, just milling around doing farm labor. Is that because I made him steward?
Valdimar is terrible. I watched him get stuck in the hatchery, teleport onto the ice, fall under the ice and get stuck, then teleport back into the fish hatchery to start the cycle all over again. It's good that NPCs don't drown.
Yes, if you make him steward he stays close to the house as a steward does. I thought that was patrolling when my other character made him steward, I just didn't know. Now I have a separate steward and Gregor patrols.
Also btw, if you lose track of Gregor or a follower at Heljarchen, check in front of the big rock outcropping in front of the house, where the drafting table is. They get stuck there often, so must be a pathing isue. I always make a wide berth of that area when I am coming back home or leaving with them. They will 'unstick' when you go in the house though, or fast/carriage travel.
Valdimar is not the only NPC flummoxed by the hatchery. Every time I go there with my spouse/follower and I go down there, he goes in the water instead of the dock. Pathing issues there too.