I have a few WWVB clocks. The ones that are on the north/south walls will never sync on their own, but east/west walls will sync just fine. I just take down the north/south clocks twice a year and lean them on a west facing wall and they'll sync overnight.
I think that most WWVB clocks just don't have the size to have an omni-directional antenna.
If I have to take the clock off the wall and move it outside, I may as well set it by hand. In any case, I've tried leaving one outside facing west and it still doesn't work. I've literally never had one of these clocks work from NC.
Meanwhile, the WiFi NTP clock I purchased just works, like I always hoped the WWVB clocks would have.
I think that most WWVB clocks just don't have the size to have an omni-directional antenna.