Great ideas. My two cents worth:

A leisure traveler, for US and Europe I take only black. Black shirts, black pants, black undies. No need to separate loads of wash should you be lucky enough to have a machine, or at the very least they mix and match well. Large beautiful scarves are useful.

For Asia, light colored cotton tees, cropped pants, plan on using the very inexpensive hotel laundry. In Mexico, check the nearest one-day full service drop off and pick up laundry. Plan on buying more while there. (Wish I had 4-6 more of those wonderful rayon drawstring pants I got recently at the Bangkok weekend market.)

Never, ever, pack anything liquid in a checked bag. This includes solid deordorant and toothpaste. It WILL leak all over your clothes.

Assume there will be shampoo etc at hotel. If not, buy it locally, or you can actually do a great body and hairwashing without any soap. Do not use bar soap on hair. (One hotel in India had shampoo in a plastic McD ketchup kind of thing which "guaranteed to make your hair black and shiny." Worked fine, and amazingly I was still blonde/brown after use.)

Have tested, can do three weeks with one hard-sided carryon that fits UNDER the seat, and a lap-top type bag for books, meds and stuff. Once you can do 3 weeks, I assume it's good for a year. Wish I had time to test that theory.

I don't like the idea of disposing of your dirty stuff along the way, and am surprised it's so popular here. Pack it in, pack it out.