It kinda depend on how the prop is going to be seen in your animation i think. If you know that its something that you will never see up close, you dont really have to create a high res map for it. However if you use a low res map like 512x512 and shoot it up close it wont look very good.

So would suggest making fairly big maps, maybe 2048x2048 and then you can always resize it to your needs.