Obviously the reason for applying a sealer to a gasket is to insure there will be no leaks, Right? However, did you know that the use of the wrong kind of sealer can actually cause the motor to seize up? The almost universal use of silicone sealers as either a gasket by itself or as a coating is not a bad thing. What is a bad thing is

the use by unqualified mechanics (read you) in ways it was not meant for and in quantities that are ridiculous.
Lets examine the photo to the right. ("Click" photo for more detail) The red circle shows excess silicone in a critical area, the head oil feed. The blue circle shows a length of dried silicone ready to break off and fall into the crankcase ready to foul the oil pickup, or worse, the oil pump! Also note the use of standard household clear silicone like what would be used on a bathtub! If the silicone blocks this passageway, EVERYTHING above the piston is landfill from lack of oil. Still skeptical? Check out the bearing. Note the cam bearing journal. The red arrow indicates where the aluminum bearing has been worn away from the lack of oil. Care to guess what a complete head, costs?