One thing to note; cold blooded critters don't need to do much of anything as frequently as we do.

By comparison we're extremely high maintenance; we have to source and actively burn a majority of our caloric intake - which requires O2 to happen - just to maintain our body temp. Chevy's body temp is more "right place, right time." Food gets scarce, if they can keep their temp on the lower end they can easily go weeks, possibly months without a meal.

As long as he wants. No one is holding his head under, if he needs to breathe, he’ll breathe.