sasuke has a high chakra reserve. maybe not as much as madara or naruto but still high. he was able to fight
madara
obito
10 tails
rikudou obito
10 tails madara
kaguya
sage of 6 paths mode naruto
it is hilarious when chapters like the recent one make Sasuke look like a whelp.it is implied in the fight against Shin that AT doesn't even take nearly as much chakra as you want to think it does, considering Sasuke said that fireball was the strongest jutsu he could use at the time.
i stand corrected, but it still doesn't say a lot about Sasuke's chakra reserves if he has to worry about being cost effective with his chakra.He never said that. In the VIZ all he says is that he'll make them talk.
The Rinnegan being active alone takes a lot of chakra. This is seen when Sasuke closes his eye to not waste his chakra, and in V.O.T.E 2 when he had to close it again by force because he couldn't control it due to the amount of chakra it took.
After using amaterasu, his eyes sometimes tend to bleed. And his eyes didn't shut down, they just became hard to use properly.