1. What cubes genuinely improve
Cubes can group outfits, underwear, children’s clothing, or laundry so you can find one category without scattering everything else. They can also make unpacking faster at a hotel. Their strongest benefit is retrieval, especially when more than one person shares a suitcase.
2. What they cannot do
A cube does not make clothing occupy less volume unless it changes how you fold or compress it—and compression can make a bag heavier or harder to close. Too many cubes add fabric, zippers, and decisions. If every item is separately contained, access may become slower rather than faster.
3. Choose a system you will repeat
Start with two or three categories and use the same locations each trip. Pick sizes that fit the shape of your suitcase instead of forcing the suitcase around the cubes. If you are unsure, test the system with clothes you already own before buying a full set.
The short version
Choose for your real route, test the decision before departure, and verify changing airline or product details from authoritative current sources.