How long for feathers to grow back?

[TigerMoon]

We had a problem with a bully hen who was pecking the other three. One in particular was left with a big bald patch on her chest.

We seem to have solved the pecking problem (using bumpa bits) and haven't seen any pecking for a few weeks now.

However, the badly pecked hen doesn't seem to be growing her feathers back. Is this normal? I assumed after a few days of no pecking, they would start coming through.

I'm worried, maybe the pecking is still going on but we're just not seeing it.

Is there any point taking the pecked hen to the vet?

Can anyone advise? Thanks!