well, him sharing Chakra with people could have just let them figure out how to combine their own internal energies and create their own Chakra.
What about in the case of Jinchuuriki? Were their base reserves forcefully expanded continuously from the moment they became hosts? or was the Bijuu Chakra wasted like when a ninja has bad Chakra control and creates too much Chakra for their Justsu during the Chakra molding stage.
Narutos was merged with kyuubi chakra and was his base. Dunno bout others.
Jinchuriki's yes they do it's been mentioned in the manga in several places that Naruto has large reserves because of kurama. The chakra seal was set in such a way that it would leak mix and become a part of the Jin's reserves expanding them over time.
If that was what Kishimoto meant then it makes no sense that traces amounts of Bijuu chakra leakage = Expanded reserves. But, what was done during the war arc had no benefit to the ones who received large amounts of Chakra.
Naruto's Torii seal was designed to merge his chakra with Kurama so his reserves expanded just a bit. As for the other jinchuurikis they were never stated to be as such, nor did they have rapid growth in chakra like Naruto did.
Exactly this.
