###If repeated castings are possible, then the odds just got a *lot* better.  

As [AngelPray points out](https://worldbuilding.stackexchange.com/a/142614/50): 

> There are all sorts of times where a partly broken object or person is no more useful than a very broken object or person. It's times like these that magic comes in handy.

The corollary to this is that if you can keep trying repeatedly, and you're not significantly worse off with a failure, you'll eventually succeed.  You went from one puncture to two?  Cast it again.  You have four punctured tires? Cast a spell to repair them all.  Your car now has a giant hole in the middle? Cast it again.  Eventually, you'll get your car back in perfect condition.

Obviously, this won't work if the "bad" outcome is worse than magic can handle (such as killing your friend, if resurrection is beyond magical means), but in that case, you're back to where we started with AngelPray's quote.