When hens molt they stop laying eggs and use the nutrients that were going to make eggs to now make feathers. Since they are not making egg shells they don’t need the excess calcium.
The basic speed that they molt is controlled by genetics. Some are fast molters, some slow. That’s controlled more by how fast the feathers fall out and a lot less by how fast they grow back. Still how fast they grow back has a little influence.
Your goal is probably to get them back to laying. Before a hen starts to lay she builds up some excess fat in her body, some more than others. This excess fat is stored energy she will use if she ever goes broody. Since a broody hen spends most of her time on her nest instead of out foraging she needs something to live on. A broody hen will normally lose a lot of weight while broody but it’s just fat stored for that purpose. Hens that will never go broody still store up excess fat before they start to lay.
I’m not familiar with any feed specifically for molting chickens but I’d guess the analysis would show a fairly low percent calcium since they don’t need a lot, probably a bit more oil than normal so the feathers are nice and shiny, and a boost in protein and maybe other specific additives for nice feather growth. The goal is probably more for show chickens where they want really pretty feathers instead of making the feathers grow back faster. There is nothing wrong with that.
I think your biggest benefit to feeding them extra protein during the molt will be that they build up that excess fat faster so they come into lay quicker after the molt is over. If none of your hens are laying it makes sense to me to switch to a higher protein feed with about 1% calcium. You are going to maintain their balanced diet more that way than adding specific high-protein treats. An 18% to 20% Starter or Flock Raiser sounds really good to me.
Even if you have some hens laying while others are molting, do this and offer oyster shell on the side. The ones that need the calcium for egg shells should eat enough oyster shell while the others don’t eat enough to harm themselves.
There are always lots of ways to do this. If you provide high protein treats watch out for excess alt as mentioned above. Many show breeders use “calf manna” as a high protein boost.
