Shed hunting season when the ground freezes everywhere.
Leaves and other organic material composting keeps the ground soft in the dense woods we can't hunt in the summer time.
Spring fed creeks and surronding areas offer fairly unfrozen ground also. Don't like taking the metal detectors out much below about 25° or so, unless it's nice and sunny.
Once the woods have frozen (that is often Jan- Feb), it's clean machines (including waxing), clean finds that still need it, and then it's research time. I become very familiar with the historical section of the county's main library and the museum close by.