Luck vs. Rare Default

Hoping someone can clarify this for me…

If I put in a Luck challenge of difficulty 0, the player will have a 50/50% of either ‘Success’ or ‘Default.’ Correct?

However, if there is no challenge, and just a ‘Default’ and a ‘Rare Default (50%)’ the effect will be the same without the use of Luck? I’m hoping this is the case, as I am trying to hide “You were (un)fortunate!”

Some experimentation later, I discovered that I was correct in my assumption and interpretation of the manual.

A ‘Rare Default,’ with there being no challenge, can still occur. If set to 50%, it (should) show up half the time (though impossible to test without repeatedly running the same storylet a billion times…)

Unfortunately - I have to rebuild all my branches where I use Luck to get a 50/50 roll, because you cannot delete a “Success!” branch conclusion. (Though you can delete the entire branch, once recreated using Rare Default & Default instead of Luck).