occasional, if you want to live with a 20 year old OS then feel free to revert to say Win3.1. Good luck on getting any recent software to run on it. You can only keep patching in new technology for so long before it all falls over under the weight of hacks to get stuff working. And your support costs only fall to zero after 10 years if your product is frozen.
mixture, exactly how much support does closed source give to the average home user, or small office user? None, aside form patches and opens source does exactly that too.