Sealed O ring & X ring chain - Factory sealed chains feature better built in lubrication from the production process but they are not maintenance free! it very is important to ensure that sealed chains are kept well greased or lubed. Both the rubber seals & the exposed metal plates and rivet pins need to be kept lubricated. A rough rule of thumb is every - 300 miles or so, depending on conditions. If used through winter, or extreme sand dirt then the chain should be cleaned and lubed more frequently. If a sealed chain is left on a bike which is not going to be used for a few months, its worth lubricating the chain first as any road salt residue will attack the chain.
Ordinary roller chains (not sealed) - When used as a drive chain, standard chain types need more care and attention in terms of cleaning and lubrication as lube will be lost much quicker than a sealed version.