Leather is damaged more by dryness and loss of oils than by water. It's true, water washes leather oils out fast and causes it to dry out stiff and hard. But leather oils also dissipate every day when it's dry, even when it's not being used. Like your skin, it simply dries out. Wind, warm air (floorboard heaters), dust, chemicals, mud, and normal wear (flexing) increase the rate of oil loss. Dry fibers scuff easily, wear against each other, get brittle, and break prematurely causing cracks in your leather. Dry leather also cuts stitching and is prone to dry rot. The solution? Do not let the fibers dry out, keep them lubed with proper oils. The frequency with which you must treat your leather depends on your usage, conditions, age, and type of leather. If it appears dry and is scuffing, it's past due! If it's going to get wet, oil it ahead of time.