I actually asked this question a few years ago, as i have the original transparency used to print a reasonably sought after poster - sent to me by one of the producers. Nothing major but a poster that sells for $100+ and sells easily, as they didn't print many, and it has great art.
So, if i had a small screening, printed a hundred posters, used ten, ALL WITH THE INTENTION of selling the other 90.
The screening is 2nd in order as far as profits would go.
So a poster that is made to advertise the movie screening, Vs a movie that is screened to help sell a poster.
Or what if I DID use them all, as wildings etc, then after a day or 2, ran around and removed them all, took them home. And then sold after the screening.
(or if I missed some and they went to collectors hands)
All just food for thought.
PS- a lot of Polish posters I would put in a similar category. Printed for a small film society screening, they might only use a few, the rest are for sale.