The tan is only a wee part of the story. Hide prep is really important...fleshing, degreasing and shaving (for some hides). Then after the tan oiling and breaking. If you're doing things like red fox, kit fox or coyotes shaving is a none issue. On the other hand grey fox , cats badgers , beaver, elk, buffalo and bear nead shaving (thining some portions of the hide). I have a seven foot diameter drum and it will break furbeares and elk to ptoduce a very good "rug" tan. For garmet tanning most industrial tanneryies use a kicker to produce the supper soft leather of fur coats etc.
Once a skin is tanned it is tanned. If it gets wet you will have hardening with most tans. There is / are an organic based tan(s) that covalently bind to the colagen in the hide,, these do not leach out when the hide is wet...these tans "hstiffen" up to a lesser extent.
Luftan, in my opinion, is the easiest, safest, and most reproducible of the inorganic tans.