This might be embarrassing, but was the Bulk Move of images available in v4 ?
Back when I was just the admin and not the owner, the previous owner told me to move the ending week's contest pictures by going to the Approve Photos process which took a LOT longer. I never touched areas he didn't tell me about just in case.
I took a look at the Bulk Move and noticed with pretty much 3 clicks set up the process to move all photos out of the current contest into Jan archives. Love that option