It's so undignified, especially the bare butts and necks; I always feel so bad for them.
Depending on the feed you use, a high protein feed usually helps with feather growth (my girls are always on a 20% chick starter with oyster on the side). I also usually hand out some wet cat food...
My LB did the same thing. She's a year and a half and it's her first molt.
She lost all her butt and neck feathers - not a hard molt, but definitely a molt - about late Oct/early Nov. Started laying again. Then thinned out her back about a month and a half ago. Started laying again. Now she's...