I have full fenders with deep front flaps for all my bikes. Three have fenders on year round. On the other two, it take minutes to put them on or take them off.
If roads are wet at all, fenders keep the bike far cleaner. Another observation I make every summer when they come off my two most used bikes is that my cycling clothes get far dirtier when I do not use fenders, even on completely dry roads. (Do a hand wash after a century sometime and look at the road grim blackening your wash water. Put fenders on and those same clothes will be far cleaner. Little more than your sweat.)
Ben