One thing that frustrates me about Luck is the fact that you burn it up and it's gone. In a life-or-death situation burning Luck is a worthwhile expenditure of resources, but for a simple +1 on a die roll Luck is too valuable to spend most of the time. While there may be ways to restore it, this makes Luck a very expensive currency and not a big impact on the game most of the time.
What if it was more fluid? I'm thinking of making Luck for all characters similar in some ways to the way it's done for Halflings, where you recover Luck after every adventure (not every day).
Think about this: a character has a Luck score, which provides a Luck modifier. Suppose that Luck modifier became more like the "action point" where a character had that many re-rolls or do-overs in a single adventure, then they would reset before the next adventure. A lucky character would stay lucky.
For example, suppose a lucky person has a +3 modifier and this could become a three re-rolls in a critical time of the adventure.
On the other hand, an unlucky person has a -3 modifier and this could become three unlucky re-rolls in the adventure. (You made the roll, now try again.
Anyway, probably too late for discussion but it was in my head so I thought I'd pass it along.