I have had road style fenders with the wire stays, and their biggest enemies seemed to be sunlight and cold. They usually lasted a couple years and then shattered during the winter. The brand was Bluemels, IIRC. It was 20+ years ago, riding year-round in South Bend IN.

Now two of the bikes under my care have Zefal "Classic" MTB fenders that seem to be made from a tougher material, and have no stays. They don't offer the same coverage as road fenders, but are wider and have held up through multiple winters, including getting banged around in bike racks.