I usually consider Determined to be a dead draw.

The majority of the events you're going to be playing don't have tests on them.

In a build where you're fighting exclusively with events they'll see a bit more play, but it's just +1 skill value (or +2 with both copies) that takes up space in your hand and that you might lose to an autofail.

There's no good skill card synergies in her current card pool to make playing around Determined interesting, like how Vincent has Grisly Totem for his On the Mends or Bestow Resolve for Carson's "As you wish" (both of which are much more less conditional skills anyways).

My hunch is that they inserted these into Marion's deck to deliberately hamper the power of her investigator ability, forcing you to draw crappy skills instead of keeping the event value train chugging.