Thanks for taking the time to help us out. This makes me think I'm missing something really important. I swear I read the book!
Here's a brief example in the context of my players encountering a hostile Iron Porcupine (3):
1st word consumed: Iron Porcupine (3) attacks to start the encounter. A player uses a word of power to avoid the damage, and generates a memory. **this actually raises a couple of other questions I've had - do hostile creatures attack the entire party, or a smaller number of targets, or is it GM's choice? Can one player act to protect the entire party or does each DA have to act individually to avoid a negative outcome?
2nd word consumed: A player then uses a word of power to engage the Iron Porcupine (3) and succeeds, filling one portion of the encounter clock and consuming another word from their collection and generating a memory.
3rd word consumed: Understandably angry, the Iron Porcupine (1/3) does a dangerous thing, and a player uses a word of power to guard against it consuming another word from their collection to generate a memory.
etc until the challenge is overcome. By my count that gets us to a possible 6 words consumed in one challenge, where the reward is one new word by default. Is it that my players are overusing their words?