Packing cubes get marketed hard, which makes it fair to ask whether they're a genuine improvement or just a solved organizational problem being resold with better photography. After years of both using and skipping them, the honest answer is: mostly yes, with one caveat.
Where they clearly help
Cubes make a backpack's contents scannable — you can find the specific shirt or charging cable without unpacking the whole bag onto a hostel bunk. They also compress clothing meaningfully with the compression-style versions, which matters more on a 38L bag than a 60L one.
Where the marketing overpromises
They don't magically create extra space — compression cubes trade wrinkle-free packing for volume, and if you're already a tight, efficient packer, the space savings are marginal. If your packing problem is "I bring too much stuff," cubes won't fix that; they'll just organize the excess more neatly.
The caveat: buy fewer, bigger cubes
A common mistake is buying a set of six small cubes and using each for one clothing category. Three medium-to-large cubes (tops, bottoms, "everything else") is faster to use daily and just as organized.
Takeaway: Buy 3 cubes, not 6, sized for categories rather than garment types, and treat them as an organization tool, not a packing-volume solution.