Doors that stick, slam or will not latch: humidity plus air conditioning
Nine times out of ten the fix is at the hinge. Years of use strip the top hinge screws out of the frame, letting the door drop and bind at the latch corner. The repair sequence is: remove the stripped screws, plug the holes with glued hardwood dowels or fit longer screws that reach the wall structure behind the frame, and re-hang. If the door still binds after the hinges are true, then and only then does the plane or belt sander come out, taken to the bottom or latch edge in light passes, with the bare timber resealed afterwards so it does not just swell again next summer. Latch problems usually need nothing more than moving the strike plate a couple of millimetres.
Time and checking: 20-45 minutes per door is normal. The finished door should close from a gentle push at walking pace, latch without lifting the handle, and show an even 2-3 millimetre gap around the frame. A soft-close or a simple door stop solves the AC slamming; planing does not.