[johndallman]

I've only used Impulse Buys with real character points that I lost if I used. A ground of friends have used a mechanic a lot more like Destiny Points, and found that there's a tendency to time-fill late in a session when they're out of points, to avoid doing anything dangerous without a safety net. Time-based Luck doesn't do that.

Both Luck and Impulse Buys make characters more willing to take risks, mostly by not worrying about bad outcomes, because they can avoid them.