Such a handy little gadget. I can think of a few more uses for them.

I'm hoping that ALL of the Time Turners in the world were not destroyed in that one day in the Department of Mysteries.

I think Dumbledore himself used a Time Turner in the third book. He was too comfortable at Buckbeak's execution, and he figured everything out too quickly that night.

Again, in the fifth book, he knew too much. How did Shacklebolt know to modify the snitch's memory? Why did he chuckle when he saw the DA list? And how could Dumbledore disapperate in Hogwarts?

I think he used them all the time. He knew things he shouldn't have know.

Saving Dumbledore might be asking a bit much. But in other things, if handled properly...