In a perfect world, every cinema screen would have the same support for every DCP. Then you could make a DCP and be sure that it would play everywhere. Unfortunately, this is not the case in reality.
Video frame rates are a common cause of problems. The only thing you can really depend on is that every cinema can play back at 24 frames per second (fps).
Modern systems can also play back at 25, 30, 48, 50 and 60fps. However, not all systems can.
If your content is not 24fps you have two options:
If your content is 23.976fps or 25fps, this is a viable option. DCP-o-matic can run your video a little slow or fast and adjust the audio so that it will be slightly at the wrong pitch but will remain in sync with the video. If your content is at some other rate, DCP-o-matic cannot convert it effectively to 24fps. There are other solutions for frame rate conversion but they are not free and they have their own problems.
Sometimes, you will only play your DCP at a single cinema. If you can test your DCP in that cinema it makes sense to create a DCP at the nearest rate to your content, then see it works. If it does: great! If not, you have to think again.
If you are distributing your content widely, to cinemas that you don't necessarily know, you are taking more of a risk. Since all mainstream content is distributed at 24fps there is no guarantee that any other rate will ever have been tested in some cinemas.