I think that depends on how well the engine has been kept so far, has it had the services on the correct intervals etc?
I'm guessing not as it's a 172 and hasn't had the belts changed yet.
Bingo! Also if your doing 6k oil changes or pushing above and beyond the 12k intervals comes into it!
we've done 5 this week and its only wednesday LOL (all rattling, not just for the hell of it)