Hard to say, Josh. Other than documentation of when theaters switched to widescreen, there's precious little information on how things were actually projected in the field.
I would believe the major chains and presentation houses were very careful with following studio recommendations. Beyond that, who knows?
However, for mastering in 2014, the directors compositional intent should be followed to the letter.
Thanks for answering my question and so quickly Bob. I completely agree that for home theater mastering (as well as theatrical revivals), the director's intent should be what is followed.
I was also thinking about how often theaters today get it wrong -- the digital revolution was sold to us as being something that would make each theatrical showing of a film precise and perfect, and that hasn't always turned out to be the case. For theaters that have always cared about presentation, I don't know that we really gained anything. For multiplex cinemas that were poorly run, we don't get scratched prints anymore, but all of the other problems associated with bad projection can still happen. And the so-called "premium large format" digital auditoriums don't use any screen masking at all, so even if the film itself is in the right ratio, you're more likely to see blank/unused screen area today than ever before.
So when I think back to how theaters were then -- a single screen, presumably a projectionist working full-time, with a movie playing for more than a week or two -- it seems totally believable to me that theaters would take time to differentiate between aspect ratios and make sure that their house was set up for 1.85:1 for this month's feature, even if last month's was 1.75:1. On the other hand, I can just as easily believe a projectionist or general manager saw the variety of aspect ratios, saw that they weren't too far off from each other, and just settled on a single ratio that best fit the room that they had and then set it and let it as that.
I honestly wish studios exerted more power over theater chains than they do. To me, it makes no sense to spend $200 million producing a modern blockbuster, another $100 million or more promoting it, and then just sending out a digital file indifferently, where the theater is free to show it at the wrong aspect ratio or out of focus or with the projector bulb too dim, or the screen not matted properly. I don't get putting all of that effort into making the film and then letting the most important part of that -- how an audience gets to see the film -- be entirely in someone else's control. But I suppose that's the model we've settled upon.
All of which is to say... I'm grateful for the research Bob does so that, at the very least, when I'm watching at home I can get as close to correct as possible.