The above image is of the most famous of Byzantine Ivory triptychs: The Harberville Triptych. Triptychs arose in early Christian art and were generally were three panels with the center larger and the sides folded in to protect the work from dusty cathedrals. The word triptych, often spelled triptic these days, comes from the Greek τρίπτυχο, from tri- "three" + ptychē "fold".
Triptychs don't necessarily fold any more. Nor are they limited to religious subjects. And the size of the panels is more open. Francis Bacon did the triptych below and all the panels are of the same size. And not hinged.
I like this one hanging together but I don't know of the left panel could stand alone because unlike the center and right one it has no strong focus.
So, why all this discussion of triptychs? Because I plan on painting one. I am leaning toward the larger panel in the center because I like the sense of balance that contributes. And I want the three panels together to look like one painting as in the middle example. But I also want all three panels to be a painting within themselves.
It is a lot more difficult than it seems at first blush. So now on to picking a subject; most likely canyons or arches. And then working on the sketch. It will govern the porportions of my canvases.