I suppose it also depends on which cinemas theyre screened in. Some cinemas have movies that have been out for 2 weeks and barely get butts in the seats, others in very high popularity areas can get a full screening of the same movie 2 months later.
My cinema regularly screens old shit, but I keep forgetting its something they do and theres not much advertising for whatever it is that theyre rereleasing.
It also really depends on the movies of course. For movies aimed primarily at children and families like Pixar flicks, I can see a lot of parents going 'yeah I don't have the time and energy to take my kids all the way to the cinema and buy expensive snacks for some old movie this week, especially when we already have seen the movies at home'