Hi from sunny England. We heat disinfect our Machines in the morning before the first patients are put on , between every new patient and after the last patient. This means our Machines are heat disinfected 4 times a day. Each disinfect takes 40 minutes.On sundays because we are closed they only get done once. As for the machines that are kept spare, we disinfect them once a day. We found that with doing this, we stopped having a build up of Endotoxins. Cathy