Some of these fuel cocks and the likes need continual maintenance... nothing can be taken for granted. All the more so on an aging aircraft
Through poor instruction or sheer laziness, most pilots never turn off the fuel valve on the Cessna 150/152. By leaving it ON at all times, the valve eventually jams itself solid and you can't turn it off without breaking the shaft. Shame if you can't turn it off if the engine catches fire or you have a forced landing. Try writing up that defect in the maintenance release and hear the screams of protest from the owner.