Are we sure that Sage Mode Hashirama isn't just a super powerful Creation Rebirth? A that's why he has unlimited amounts of heal because of his enormous Chakra stored in the seal. :
Tsunade's Sage Mode Gaara | Anime Meme on ME.ME
Tsunade | WRA
SASUKE RETSUDEN MANGA ADAPTATION β β on Twitter: "Manifesting learning more about the Shikkotsu forest and possible slug sage mode for Tsunade and Sakura ππ½π― https://t.co/bvj6zU3RZs" / Twitter