Stella Clark is on the card, so it must be good for her, right? True - at least until she becomes a Quick Learner, which she probably wants and with 2 copies, +3 instead of +2 for 1 turn is not that impressive. Aside of early-campaign Stella, Gritting Your Teeth seems mostly useful for and pseudo-.

If you want to get value out of Gritting Your Teeth, you want to take multiple tests after playing this card. In the ideal scenario, you fail a mythos test (that is a thing) and get as many +1 actions as you can (also happens to be thing).

More value comes if you also use cards that care about testing two skills. Accidentally, most of such cards happen to be .

So we're looking at investigators who can get the most value of Gritting Their Teeth. Rita Young likes Tricks that add her to a skill test (and can hide an Ace in the Hole). Similarly Bob Jenkins has the right cardpool and stats. Certain Dark Horse Preston Fairmont builds can appreciate this, getting to a reasonable skill value and having ways to generate actions. Patrice Hathaway can reasonably run this card as a with potential extra use (see the synergy with Grisly Totem?). Possibly helpful also for Jenny Barnes and Finn Edwards, but they probably find more impactful cards as their 5 off-class pieces.

Well there are reasons why this card doesn't see much play - but at least there are investigators who can make it do some work. And maybe it's the that makes the real difference between a garbage card and not that good, but never wasted and situationally quite helpful card.