Do you know how long a title has been downloaded?
It all depends on the title. There are those that buy off after a few days and there are those that last a month.
Netflix also has to buy a license for the offline function, so it's not so easy to answer.
So, as I said, is different. This license even describes how often you can download the film.
But many (I've done so far) have been walking for about a month.
If you clicked on the movie, it will go down faster. Then you have to have a quick look at it. So don't look in and then think that you will only really see it in a week. Then it's gone again.