Because of the rate of expansion between cylinder heads metal and valve covers are different every car will need valve cover gaskets replaced at least once in it’s lifetime. The seal/gasket will break down over time and your engine will leak oil from here.
Valve cover gaskets are typically made of a cork/paper composite or a rubber seal. It is key to achieving a good seal to not damage either mating surface when removing the old valve cover gasket/seal. It is important to fix this leak as it can cause damage to other parts of the engine. Valve cover gaskets are typically on the upper part of the engine so when the oil leaks gravity pulls it down and it can get into spark plugs, alternators and other places that should not have engine oil on them.