In my third year of classes at the 
Joe Kubert School of Cartoon and Graphic Art, we had a class taught by Joe himself. One of our assignments was to do five pages from a comic, as well as a cover. I decided to do a Superman book.
Big surprise, right?
I've got the interiors somewhere, but I couldn't dig them up. What sticks out in my mind was the cover. I got this idea to impose two characters over a three-point perspective background. This was back in my George Perez crazy detail phase.
Backgrounds weren't my favorite thing, and while I understood perspective, using it in a panel always seemed to trip me up. So, I drew a complicated background on a separate sheet of tracing paper, and blew it up to ink it. But, when I made it larger and put the characters in front of it, I thought it looked cool as it was.
But, the assignment was to ink the cover, so I inked the background on a sheet of vellum. When I showed it to Joe, he said "You know, the pencilled version looks better. I'd keep that" So I went back to the enlarged pencils.
Happy accidents, I guess.
What always got me about this assignment was some fellow classmate who didn't like the cover. He said he didn't like those tight three point perspective covers where the buildings were so close to each other that there was no room for streets or anything. I thought it worked. In fact, I had ideas of drawing stock backgrounds like this and dropping flying characters on top of them.
So I was surprised and a little validated when I saw DC do a series of covers for the Superman books featuring the same idea just a couple months later. (And no, in no way am I suggesting DC borrowed my idea. They never would have seen it. It was more, as noted philosopher David Addison once said "Mediocre minds think alike.") I can only find one of the covers online, so my memory may be off. But I'm pretty sure that all the Superman books that month used that idea.