A starter that cranks a bit slower than it used to, or hesitates once in a while, will usually hold out long enough for you to book a visit soon. Grinding can't wait. When the drive gear doesn't engage cleanly, it grinds against the ring of teeth on the engine's flywheel, called a flexplate on automatic transmissions. Chip enough of those teeth and even a brand-new starter will grind or fail to crank at that same spot. Replacing a flywheel or flexplate usually means removing the transmission, which turns a starter job into a much bigger repair.
A starter that sticks on after the engine fires can wreck itself and overheat its cable, and a shorted one can drain a battery overnight. Cranking a failing starter again and again does damage too, overheating it and flattening the battery. Caught early, the repair stays at one part. We inspect the starter and the flywheel teeth and send photos before recommending anything. Hear a grind, a whine that keeps going after the engine starts, or smell something hot? Get the car to the C&C shop nearest you, and if it won't crank at all, call that shop about a tow.