There are several ways to gain exhaustion outside of combat, like forced march, swimming, diseases, but I can find anything related to fighting or combat causing exhaustion. This seems rather odd since fighting a horde of snarling beast seems like it should be one of the most exhausting things possible!

Does there exist any systems that would allow for PCs to gain exhaustion for fighting? RAW would be preferable, but any well-reasoned home-brew is acceptable as well.

There are several ways to gain exhaustion outside of combat, like forced march, swimming, diseases, but I can find anything related to fighting or combat causing exhaustion. This seems rather odd since fighting a horde of snarling beast seems like it should be one of the most exhausting things possible!

Does D&D 5e have any rules systems that would allow for PCs to gain exhaustion for fighting?

The few that I have found, according to RAW:

1. If PCs don't have enough food or water for the day, they will gain 1 level of exhaustion.
2. Getting a disease (DMG p.257)
3. Travelling to an Outer Plane (DMG p.59, Optional Rules)
4. Extreme Heat and Figid Water (DMG p. 110)
5. Swimming
6. Forced March
7. Chasing Someone (DMG p.252)
8. Side-effects of various magic items.

I find it odd that there are no rules for prolonged combat or casting spells causing exhaustion. Am I missing something? What other situations cause PCs to gain exhaustion?

There are several ways to gain exhaustion outside of combat, like forced march, swimming, diseases, but I can find anything related to fighting or combat causing exhaustion. This seems rather odd since fighting a horde of snarling beast seems like it should be one of the most exhausting things possible!

Does there exist any systems that would allow for PCs to gain exhaustion for fighting? RAW would be preferable, but any well-reasoned home-brew is acceptable as well.