#5 for underwear and anything that tends to get dirty quickly. Up to 7 days, barring spills and other incidents, you should be able to manage just with that.

For longer than 7 days, you probably need a proper laundry.
Laundromat are a bit of a chore, yes. But in some countries they also have completely managed laundry services where you leave it in the morning for example and take it in the evening or next day. Did that in Mexico last year. Very practical and dirty cheap.