For me, headwear is more about keeping my ears warm than my head overall.

100% ears are hard to keep warm, but the head generally isn’t. Heck, I’ve got a very ventilated Specialized helmet, and with just a standard helmet liner that covers my ears and a light buff, I’m fine all winter. If I need more warmth, I put on a thicker buff, but even that often comes off once I start riding.

This way, I can use the same one helmet all year without any “tricks” or second helmet.