I don't think it's incorrect that some don't regrow until a molt. I'm not doubting your habitual picker, but I have a hen who has been half bald since last summer (2013) and is just growing feathers in the last week. I don't have pickers thank God, just want you to know it is possible.
Unfortunately I think I've spotted new ones coming in then they're gone
I had a similar issue with two of my birds. I also purchased the clips from someone in Australia. I didn't use them. I gave them extra protein in the form or cooked chicken or scramble eggs. I removed them from the population for 1 week fed them protein ,It took a week but the behavior stopped. Good luck
Did the protein route too. No difference

glad it worked for you though! It's a serious pain in the butt to deal with.
In reference to feathers growing back, there are two categories. If the perverse picker plucked feathers cleanly out by the roots, they will grow back before molt. If the villain merely broke them off above the skin, they won't grow back until the victim molts.
Kouros, feather picking seems to be interrupted by changes in routine, but beware it may be fleeting, and the behavior may resume.
Just today, among the Fearless Four, the Sussex thugs who warrant their own pen, they're such bad@#$%^, Geobett has resumed her evil, feather picking. Actually, she began with me, pecking my hand whenever it got near her beak. Today she is liberating feathers. Peepers will be installed before the day is over, though the device has limited effect on her.
Flo is also resuming feather picking, although she does respond to my hollering at her to stop. At least temporarily. It's Joycie's "Gaack!" that alerts me, as Flo doesn't dare molest anyone but her.
I'd love for everyone who has joined this thread to watch to see if feather picking seems to be a seasonal occurrence in their flocks. Is it ramping up after having been dormant all summer or whatever the season is where you live?
Yeah, she's picked them clean for sure, lol. I'm so upset with her right now because I treated all the girls and she just moves over to untreated areas. Ugh.
For me it started for two reasons, I think. First, I used to have a rooster. He had a favorite hen and started damaging her back feathers. Long story short, I found him a new home. And we had a very long very cold winter. Towards the end of winter, having been only in their run and the one hen already missing feathers I think this is why it started.
While they free range none of this happens. It does still happen if they are confined in their run (which is pretty large) or in the coop (in the morning I believe).
What drives me really crazy is none of the girls being feather picked do anything. I swear they just stand there and let her do it.
Peepers are on the way. I hate to do it but I guess it has to be done.
Something I noticed last year when I culled a bird that was grabbing feathers... when I cleaned her out and cleaned out her gizzard, I noticed that some feathers had made holes in the gizzard lining. That was quite amazing as that's a pretty tough membrane! At least I think the feathers made the holes, there were feathers in the holes but they could have just found their way there with the gizzards grinding and moving everything around.
I'm pretty sure that holes in the gizzards could really cause some internal problems.
I believe it! I probably won't ever open the picker up when she passes but I'd bet money that there'd be feathers in there! I'm kind of afraid that all her plucking and eating of the feathers is ultimately going to be her demise
Here's a photo of what they used to look like.....
And here they are now.....I know horrible

they all have bare butts like the one in the photo. Notice miss fancy pants....otherwise known as The Picker!
This is Cindy. She's the favorite to pick off of apparently. She was also the "favorite" of the rooster.