Used to travel for work 3 weeks a month and worked with a group of folks who took pride in traveling light. I learned to never pack for more than 6 days. After 5 days either do the laundry or use the hotel laundry service.
And some people for whatever reason think that everything you wear once needs to be washed before you can wear it again. Break out of that mindset. You can usually wear pants and shirts several times if they aren't sweaty and don't have food spills or something like that. Hang them up or fold them at night, maybe touch up with an iron if they are wrinkled.