In the medieval era in Europe few were generally professional, in the sense that it was their full time job even in peacetime. Like you said the Kings retinue would be one of the few exceptions. Since the collapse of the (Western) Roman Empire there just wasn’t the concentration of resources in Europe for maintaining standing armies. Most were effectively a reserve force, somewhat akin to the. National Guard in the US hat could be “called up” in the event of a war.