Thanks all.
We went again today and walked (intentionally) the same in/out route 2 times. That's four passes of the area I frequently see them.
1. Way in. Nothing.
2. Way out. Spotted two hens (too far out to shoot) running then flying downfield.
3. Way in. Nothing.
4. Way out. I send dog to other side of briars. Dog gets birdy, real birdy, flushes a rooster RIGHT in to me. Perfect day!
Moral: you might miss them, they might come back, they might have missed you... just stay alert and bushwhack 1 step above your comfort zone.