The fronts have a wear tab that will touch the rotor and let you know in no uncertain terms, it sounds like nails on a chalkboard. That usually happens around 30K for me. As for the rear, I'm over 150k on the original rear shoes. I'm thinkin the wheels will fall off before I replace them.
"Political correctness is a doctrine, fostered by a delusional, illogical minority, and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end."