I cycle them onto dirtier tasks (eventually chain cleaning duties) and then bin them.
I usually use new for buffing, after a few buffing uses they are used for drying, after a few drying uses they are good for application, after a few application uses, they get used for cleaning around doors after that they become general purpose rags and then eventually become dirty job rags.
I always rinse out at a minimum after use until they become rags.