It's a fairly expensive (in xp) skill card, so it's pretty easy to just avoid it. The fancy thing it does is 5 xp for Always Prepared, which is a lot even if you've got 2 copies, and it's limited to once per round. Usually it's pretty similar (+/- 1 symbol) to Unexpected Courage, and the traits portion limits it to monsters or treacheries, and can't be used to investigate or do tests on location cards.
Humanoid and Monster traits will get you a card that's useful against a bit under 100% of enemies, and enemies are only around 1/3 of the encounter deck. Adding Elite and Ancient One means it will give you 5 symbols against most of the more difficult monsters. The good news is, those 4 traits will get you almost all enemies (and double coverage against difficult monsters) in all campaigns for 3 xp. I'm not sure what combo's you would need to cover all of the tests in the encounter deck, but I can't imagine 4 traits would be limiting if you're careful.
Nemesis instead of Always Prepared (or with fewer traits; elite covers the monsters you'd want to use it on) sounds useful if you're willing to have a card in your deck just for fighting difficult monsters. Not a bad plan.
If you can find the traits that cover all of the really nasty treacheries, Mythos-hardened might be a way to thin the encounter deck. But that requires knowing about them ahead of time.