If your image can be folded in half(vertically, horizontally, even diagonally in some cases), and the vast majority of it overlaps, it's probably great for the group. An example would be a perfectly lined-up shot of a building, but maybe there's a person or a tree off to the side, or a few lights out in the windows. It's still mostly symmetrical.
There are times when a submission will be denied because of a bad crop, or too much going on that doesn't line up. Please don't be discouraged if your submission is denied without a message as to why. And feel free to ask!
I'm always looking for contributors with a good grasp of symmetry, so feel free to join as a contributor if your gallery shows you know what you're doing, and don't mind taking a few seconds of your DA visit to vote on submissions occasionally.
Thank you to everyone who has helped the group to grow. If you have any suggestions, feel free to comment them below. Cheers!