How many days in a row can a sweater be worn before laundering, provided an undershirt is worn and you're not exerting yourself, sweating, or otherwise soiling it?

How many days in a row can a sweater be worn before laundering, provided you're not exerting yourself, sweating, or otherwise soiling it?

How many days in a row can a sweater be worn before laundering, provided an undershirt is also worn and you're not exherting yourself/sweating in it?