After 300,000+ miles of bicycling since the early 70s, have never utilized fenders.
Cycled in 30+ states and he worst wet weather we've experienced was on a tour on our tandem by the Grand
Canyon in northern Arizona.
A real soaker, driving winds/rain and no place to hide for many miles.
Worst part was trucks whizzing by at 55+ph and throwing sheets of water on us as they passed.
Threatened to drill holes in our cycling shoes so the water could run out!
Stoker on tandem was semi-protected from tire splashings by rack trunk on our rear carrier but not from driving rain.
When we got to Flagstaff we stopped at the first big reastaurant for coffee to warm up. Waitress felt sorry for us and gave us free pie!
No plans to use fenders.