KYF.. Tsunade's regeneration is Automatic there because she activated the Byakugou.. without using hand seals. the jutsu is activated .. not the markings of the jutsu on her body. while activated the jutsu heals her instantly .. but if you remmeber when the tree landed on her the seal wasn't activated and katsuya offered to stick her back together. the jutsu has to be activated.
Neji and Hinata learned to activate the Byakugan without seals.. remember they used to have to do hand signs to activate it. but the Byakugan isn't on till they will it so. same with Hashirama. if they don't activate the jutsu . it wont be on automatic healing.
Some cars have cruise control but the "automatic acceleration" doesn't work until you turn it on
for those of you who don't understand.. I'm coming from an illogical perspective so your logic won't fit my argument .. it'll only give you a headache.. remember ..belief doesn't require a co-signer There Is A Fine Line Between Genius And Insanity , I Have Erased This Line ! If I were you I'd hate me too.. I am the HUMAN RASENGAN!!!
The power of despair is great in you.
LOL I'M DYING BACK HERE