The latter is usually far less expensive. If fluid is found on linings, they must be renewed. Wiping or sanding off will not be enough because fluid sinks into the material and will surface when the linings get hot under braking. Disc pads can sometimes be seen without the need for dismantling. All the same, I would advise removing and checking them.
Flexible hoses become soft after a while, resulting in a spongy pedal.
Check all hoses visually and by feel. Then get an assistant to put pressure on the brake pedal while you watch each hose in turn. Look for leakage or bulging. If one hose is shot, renew them all. Drum brakes must be adjusted before the system is bled.