Inosuke puts it best at the end by telling Zenitsu he might just want to sleep during every battle. And while that would make him more powerful, it would end up crippling Zenitsu.

Zenitsu fights while asleep in Demon Slayer, relying on instinct and Thunder Breathing to unleash incredible speed and power beyond his waking limits ...

Demon Slayer: Kimetsu no Yaiba has officially brought Season 4 to an end, and its final episode is setting up Zenitsu Agatsuma for his final fight coming in the Infinity Castle arc! Demon Slayer ...

Demon Slayer: Kimetsu no Yaiba – Hinokami Keppuutan – Zenitsu Agatsuma and Inosuke Hashibira trailers, screenshots The "Thunder Breathing" and "Beast Breathing" users.