3 hours is probably getting towards the upper limit but it's hardly historically anomalous. Lawrence of Arabia was over 3 1/2 hours and other "epics" of that era were often in the 3+ hour range. (Though movie theaters often had intermissions which most would probably never do today.) Live theater (with an intermission) is often in that range as well although many newer plays seem to be more like straight through 90 minute length.

Definitely with the intermissions. But I really mean that I often like to stop a long movie, think about it awhile, and then come back to it later. This is how short TV series work, for example. This is also how books work, by their nature. It's a kind of "intellectual digestion" - an intermission is good, but a night's sleep is even better.

Yeah, but no way really to do that for a theatrical release. You can have a Part 1 and a Part 2 spaced a year+ apart if the total length is 3 1/2 to 4 hours a la Dune. That's not what you're asking for though.