Back in the day, intermissions were not uncommon. Even kid's movies like CHITTY CHITTY BANG BANG and DOCTOR DOLITTLE had intermissions. (I still remember the pre-intermission cliffhanger in the former, way back in 1968.).
Of course, this was back when double features were still routine. So seeing a single three or four-hour movie was equivalent to catching a double feature at an indoor theater or drive-in. With an "intermission," as it were, between the first and second features so you could got to bathroom and/or go buy more popcorn.
Triple features were less common, but hardly unheard-of. Still remember seeing the first three Bond movies in one go, and the first Planet of the Apes movies, not to mention a memorable night watching TROG, VALLEY OF GWANGI, and WHEN DINOSAURS RULED THE EARTH all in one night.
I think the last movies I saw with intermissions were GANDHI and REDS, back in the eighties.