According to Tazz :
Yes. And no... ;-)
It's reasonably common to upsize the conductors a notch or two for various reasons - eg: reduction of resistive voltage drop on long circuits.
However, it's expensive to do, and in many cases you can run into situations where the wire size exceeds the permissible range on the devices you connect it to. You're going to flunk an inspection with 0000 wire on a 15A outlet for example.
The inspector may ask, for example, "why the heck are you using
10ga on a 15A outlet?" You'd better have a good answer, or the inspector may flunk you for workmanship."The circuit is so long that 10ga limits my voltage drop to 3V" is a good answer. "I had a chunk laying around" is probably a bad one.