Another aspect of this is when you only know about the failure after it has happened (such as with segfaults that can't be reproduced with tools like valgrind). Being able to use something like `rr` to record the entire runtime and then rewind it to the point where the program explodes can be a life saver.

I'm not big on using a debugger but when all else fails, having access to one can be the difference between a swiftly identified and resolved bug and weeks or months of hair pulling and stress.