In the gamebook, not every move a player can choose will require a skill role. Sometimes they just have to click "Next" to advance the story, and the story can be made less linear by introducing a randomness on what might happen next. I was thinking of whether or not this could be a visible "Luck" attribute, with a "lucky" character having a better chance of what would essentially be less or easier challenges in forks of the story line.
In thinking about this, it seems like luck in this case may be redundant to other attributes. A lucky character may have less encounters and therefore rely less on a Strength attribute, while an unlucky character will need a higher Strength attribute to be successful.
Perhaps I've just answered my own question?