Out of the main medical buildings, the Infirmary has a significant advantage over Medical Posts in terms of patient capacity and heal/cure speed, and can also natively cure Gravely Ill patients, even without Radical Treatment. However, there are alternatives. With Faith laws, the House of Healing may be used to heal the Gravely Ill and also has a large capacity. And if there are enough Engineers and space available or few citizens are getting sick due to cold, it is quite acceptable to just place more Posts instead.