Somebody: "So which one's Ao?" 

Somebody else: "Blue hair, stolen sharingan, right?" 

Third Somebody: "Nah, byakugan, it's the... right eye I think? The one under the eyepatch, anyway, which is admittedly a good trick."

S: "Really? Wouldn't having to activate the byakugan to see through the patch slow him down a touch?" 

TS: "Nope, transplanted doujutsu don't hook up to the recipient's chakra system properly so they can't turn them off, they're just always active, so the eyepatch doesn't slow him down any."

S: "Okay, but wouldn't having the byakugan active constantly be exhausting?" 

TS: *shrug* "Maybe he's a chakra tank." *pause, consider* "Or a moron." 

Shisui, popping his head through the doorway: "Or both!" 

TS: "Or both."