I travel all over the world in multiple climates for up to a month with one check-in suitcase and these are invaluable. I am off to India and Bhutan, and require different clothes for Kolkata (high in 80's) and foothills of the Himalayas (10,000 feet plus altitude and lows in 30's) and these fill the bill. I pack according to area/climate, so I can easily find what I need, put what isn't needed in a drawer (or leave in suitcase) unsealed and when required due to an "early" (6 AM) flight/train can repack in 10 minutes.

I use them for little trips with one carry-on and they are equally useful.