Some rewards can be worth certain penalties (pain) if within certain thresholds. Exhaustion fatigue can also play in.

You can of course boil them down to a single number, it just produces less nuanced types of decisions/operations, as it can’t differentiate between a cheap, painful, but bountiful choice and a expensive, no pain, mediocre choice.

I think there needs to also be a concept of death—penalties from which recovery is impossible. Nonergodicity seems to be a requirement for the development of antifragility.