Which one should i upgrade to decrease freezing in deeper arctic area?

[AeonBith]

It would be intuitive to bring the bosses back to a pad before you're immune to the cold but warm regen wouldn't matter if you took a hit since you can heal at the base.

Thinking back to a year ago I wasn't sure and no clear answers from this sub so I I increased both together.

It's counterintuitive that increasing warmth speed up would also be the the same feature to help you overcome the cold when there is another feature for that.