Sometimes, it's the easiest things that give you the most trouble. For example, the invulnerability of Superman made for an easy escape out of whatever trouble a writer might have written him into, but it's hard after a while to come up with things that would pose a threat to an invulnerable person. That's why they came up with kryptonite. True story.
Time travel is another big problem that causes more problems than it solves. For example, it gives the writer room to come up with ideas beyond the confines of Gotham or Metropolis, but one must then deal with the infinite possibilities it creates.
For example (and you knew I'd have an example), World's Finest #132:
It always amazed me when Batman needed to time travel for an urgent mission. And it wasn't just to keep DC Comics from allowing Jack Nicholson to play the Joker back in the 1980's.... oh no, it was always for something very far removed, like 15th Century Italy. As of this writing, I haven't finished reading this story, but I can't wait to see how they justified this.
At this point, you can see the problem. If you send someone to another time with a button that will yank them back to the present when they're ready to come home, they will either immediately re-appear or they are lost forever, presumably dead. Yes, probably dead. But at the very least, they are lost forever or they would have been back already. You didn't send them to another planet, you sent them to another time, and since time is relative, their absence is conclusive evidence that you sent them to their deaths. Nice work, Professor.
But Superman, contrary to what others might have us believe, is an idiot, and he goes right along with the idea:
Now, I'm not sure how he navigates time without a machine to give him an idea of where he is. I'm pretty sure that God didn't obligingly put decade markers in the timestream, so I'm not convinced he's even traveling in the right direction.
But, there he is. He left 20th Century USA, and finds himself in 15th Century Italy. Why he didn't land in 15th Century USA, I'm not sure.
Now again, considering how user-friendly the timestream was, I think Superman could have easily just deposited himself at the moment in time when Batman and Robin appeared. His presence could have saved them a lot of potential difficulties, not to mention their lives, because as we have already conclusively established, they are dead and lost forever.
My head hurts. Let's finish this tomorrow! Good day, my lovelies!