Using the treasure generation table, if it says something like "50% any 4" under Magic Items, do I roll the 50% chance 4 times, with each determining whether a magic item is present, or do I roll once, and you will get either 0 or 4 magic items?
Not and autarch but i think its the second option
According to Alex in this post, it is the second.
I personally prefer to do it the first way, because I don’t mind rolling more and it more predictably generates results closer to the average.
I vote whichever way gets us more treasure! (Knowing your rolling, probably the one with more chances :D).
I'd probably vote for 1st option just because I dislike all or nothing, but Alex confirmed it was the 2nd...so swing away!
Every campaign is a law unto itself! Also the two generate the same results given enough rolls, so pick the one you like!