Yellowjackets walking straight into my hive at dusk — how narrow should the entrance be right now?

Third year in the North Carolina piedmont, four hives, and the yellowjackets have hit their stride. During the day the guards handle it fine — I watch them tackle a wasp and drag it off the board. But at dusk, once the field bees are in and the guards seem to thin out, I've stood there and watched yellowjackets walk straight through the four-inch reduced entrance like they own the place. Three went in, one came out carrying something. All four hives are on reducers already, the big opening. Do I go down to the small notch on everything, or only the weaker two? I've heard "one bee width" for robbing but I'm not sure whether that applies here when the colonies are strong and still flying hard in the afternoons. Don't want to bottleneck them during the last of the goldenrod.