For my part i think that the favor has an influence, but that it is far from being the only one concerning the chance. Or even that it is "major".
From my own experience:
1. I farm: The Job of Halycon for over 13 years. When i saw the debate on the favor a while back, i tested it out there. I never had so many platinum wands (in short i never had any). But i was only doing it during the favor. When i took this farm outside the favor as well, the rate dropped. But at the same time, several years ago, the favor was present 24/7..
2. I think that the rate of drop of rarer items, is more present the first time you discover a zone or a coop (name on the map that is discovered). Then the more we go there, the less these rare items will fall. But this is not equal depending on the object, 2 examples:
- Zehtuka's Pack: I wanted to have this item that randomly drops to NF. After getting one at a place i remembered well, i farmed that place. Couldn't get one, even after many hours and hard work. Then i realized, after dropping it +12 times, that it is impossible to drop it a second time with the same character. It's explicit, it only takes 1/2 hour - 2 hours to get one the first time, never a 2nd after dozens of hours and that systematically with every PvE character.
- Ghostly staff inscr. on NF Dryder (no DoA): Nothing to do with the Chestrun, i was killing NF Dryders for the blue low req. (eternal shield-bow & storm bow). I see a few Ghostly Staff fall at first (3-4), then nothing, never again. I killed several thousands of them, never a Ghostly Staff fell again, while the other skins mentioned and associated with Dryders fell regularly.
Anyway, in all of this, as much favor, as going to a place for the first time or going to a place you haven't been in a long time, not dying, leaving the game afk in the area for quite a while, etc, etc, always makes me feel more fortunate. But i think above all, as said at the beginning of my message, that there are many luck factors that add up to each other. It remains luck and determining the importance of each one independently of the others and its influence is almost impossible.