Tanning no matter what method can be done in a relatively short time. I have used 2 methods when I used to do taxidermy. When I first began I used a dry preserve which means I fleshed the cape out completely and then would rub a dry preserve like borax into the fleshy side of the cape until it no longer feels wet and as soon as I get this done the cape is ready to be used on the mount. When I mounted deer using this method I could do 1 a day by myself comfortably but if I was behind could get 3 done over about a 10 hour period fro?thawed cape to completed mount in drying phase. Of course the dry needs at least 2 days and I prefer a full week for the clay to all be set.
Other method I used is a formic acid tan. This method starts by getting the biggest majority of meat off of the cape and placing the cape in a formic acid "pickle" for at least 24 hours. If you go longer the cape gets stretchier but hair patterns may get "off" when trying to put too small a cape on too large a form. After the pickle you have to bring the ph down ans is done by adding soda ash to th pickle and is usually a 3 day process. After you get through with the pickle you can shave the inside of the cape with a fleshing machine as the "leather" will be plumped up and needs to be shaved down thin to prevent "drumming".
After the shave I let the capes dry down a bit and then I "stake" them by working the cape over a rounded wooden table edge by hand to break the fibers down and make it more pliable. Once the staking is completed I place the cape in a drum of dry sawdust that rotates slowly to remove the moisture and once this is done I can shake out the cape, do a final trim, mix glue and go to mounting. To get a cape ready in this method is about a 5 day process but you can do several at a time and after the first week you can have several ready to mount and the hair is "locked in" at this point so you have time to do things...
Dry preserve tends to "bleach" over time IMO but it is not excessive. Dry preserve can also crack if the deer is used in too dry an atmosphere such as around a fireplace. Formic tan seems to be better in these aspects.
I no longer mount deer for myself or others as I have a full time job and try to get things done on the Property when I am not at work and a taxidermist busiest time taking in heads and skinning them out...
Here are pics of 2 dry preserve deer I mounted in 1995, I thawed out of the freezer and mounted in the same day fleshing, turning ears, dry preserve and then mount...