The most overpowered character in One Piece so far is the second son of Charlotte Linlin, Katakuri. The anime makes him seem like a god who can glimpse into the future using his Observation Haki whenever he wants. I always thought that using any form of Haki for long periods of time tires the user. Moreover, Katakuri doesn't seem to have any problems doing this.
I don't understand why Katakuri has been able to sustain his Observation Haki for so long without even getting tired. Because right from the moment he came for the wedding, he was using the Observational Haki to glimpse into the future and then he's been fighting Luffy (with normal color of arms haki) for so long and yet he isn't showing any signs of fatigue.
Wikia even states that
It is revealed that like Busoshoku Haki, Kenbunshoku Haki can be depleted if used too much.
But then I feel like Katakuri has overused this Haki and yet there seem to be no negative effects.
Can anyone clarify why Katakuri seems like an exception to this rule?