Depends on who you are and who your ex is... It's possible for people to be involved, come to a realization mutually that they don't work as good as they initially thought, and part ways amicably and be able to remain friends. It is just SUPER rare for all kinds of reasons including, many people can't handle it... it wasn't mutual (one wanted to break up more than the other)... one decides later they miss being with someone, anyone, and it's easier to turn back to a previous partner than someone new... and I could go on.
Nothing wrong with considering it IF you're both mature about it... but don't go into it with blinders.