A couple of things came to mind recently.
In my photographic life, we have shifted from a “portrait orientation for magazine cover” process to a “horizontal to match screens” expectation. e have also gone through several preferred formats to end up pretty much where we started.
In my formative years, you always had to shoot that portrait orientated cover shot image in each set. No good getting the cracker of an image in horizontal, that would only ever be a page sharer or maybe a centre fold if you were lucky, but without the cover shot to sell the mag, no-one was going to get to look in the centre.
Right shape for the shot on this occasion and used to help determine if the touch was made.
In my current role, I have to shoot mostly horizontally. This is because of the obvious landscape orientation of a screen, but also allows a portrait to be extracted as needed.
I find portrait mode better for long lenses though when shooting sport.
Half a cut off body with room each side in a horizontal composition makes little sense, but a tight top to bottom shot feels right even if too tight. You have the same sized subject at longer distances, but effectively gain the “height” to your image of a shorter lens used horizontally.
The action was too fast to switch to the camera with the shorter zoom, so I just followed and shot.
Another that would be pointless in horizontal. I am often surprised how close they can get with a 600mm equivalent pointed at them in this orientation. The next phase was a quick try.
4:3 ratio is older and more logical than the now common 3:2 ratio. When 3:2 reigned (35mm film), the risk was always that even your portrait shots would end up losing a little length (or height). Look at a national Geographic cover. They are 4:3 ratio. I am lucky I guess, that with 4:3 in a 3:2 world, I am closer to one of the true formats, square*.
*For me, there are only two formats, square and wide screen (16:9 or more). Sure was very popular with medium format shooters, who had quality to spare, because it could be effortlessly made horizontal or vertical. Wide screen is just more cinematic, dramatic and evocative.