I purchased these last year and they changed my life.
https://www.amazon.com/Veken-Packing-Luggage-Organizers-Upgraded/dp/B07G2432R1
@conmama, thank you for sharing your experiment. I consider myself a good packer and am doubtful I would fit more in with bags (unless I buy compression bags). I do think I should be able to figure out a way that packing cubes will help. In particular, I sometimes find myself rummaging around for my undies, socks and pjs. Putting them in a cube should be something that should help. The jury is out on shirts, pants, etc. I’ll see in February when I go to NY…we stay in a place where there’s nowhere to unpack so I just use my suitcase.
I put similar things in soft or rigid nylon mesh bags or stuff sacks, depending on the items, size and what else I’m packing. Since I like being able to see things at a glance I generally favor mesh over stuff sacks.
One tip that really helps me is my pharmacist was able to give me small ziplocks with my Rx printed on a small label attached to the tiny ziplock so the pills take up MUCH less space than a bunch of pill bottles.
For supplements, I write the different ones and description on a snack bag with a sharpie and put them all in. If TSA wants to confiscate my supplements, they can.
My medications still take a lot more space than I’d like but that’s not likely to improve.
@collage1 , I’ve read the compression cubes will wrinkle clothing terribly. The small ones are great for undies, though. I have to say I really like my regular cubes in a checked bag where I have the room.
My compression cubes don’t wrinkle my clothing, but then I tend to pack clothes that don’t wrinkle for travel anyway.
I find rolling items in compression cubes prevents wrinkles. Fresh dry cleaning bags can also be rolled with items prone to wrinkling with good results. I swear by packing cubes; they are great for organization.
In order to use every inch of a suitcase, small items can be positioned under the cubes, between the spaces for the handles.
I think while saving space would be a great perk, I’d like the cubes just even for organization. We travel often to our lake cottage and because we are driving I use a large duffle for my stuff. I think some on the small side “cubes” would allow me to pack by category (tops in one, bathing suits/pjs in another, etc.) and make finding what I want easier - just pull of that category cube.
I agree that the big plus is the organization. When I go down to see my parents there really isn’t a place for me to unpack. With the cubes, I can just easily pull what I need without making a mess of my bag.
I love the way packing cubes keep your clothes organized while traveling; they act like separate dresser drawers.
They are especially useful when you are traveling to several different locations because you don’t have to keep packing and unpacking
I love them for the organization in a suitcase and additionally for stays in hotel rooms. If we just stay one night, I don’t unpack, but for multiple night stays, I’ll pull the cubes out of my bag, unzip them and arrange them in the hotel dresser drawers. That makes things easy during my stay and packing back up is so simple (just zip and pack).
I normally pack my clothes in nice plastic bags (saved from shopping trips) by clothing type. These bags take almost no room, don’t have a fixed shape, don’t have to be zipped and unzipped, and it’s easy to pack a few extra ones for dirty laundry, wet clothing, or new purchases, and just throw them away if wet or dirty. I don’t really see how cubes would be an improvement, but maybe somebody could explain?
For me something I would look for would be cubes that are somewhat see through. I want to see (and remember) what I packed, what I want to select. I also like that they can be fully secured, no open ends. I realize you could twist tie bags or something as well.
Plus, cute packing cubes!! 
Convenience (easy to put in drawer if needed and the items stay rolled) and visibility. And no plastic bags to go to landfills.
Our packing cubes are first gen Eagle Creek as well. The dimensions are set so that the smaller cubes are 1/2, or 1/4 of the largest cube. This means that they will stack neatly into a suitcase or hotel drawer.
I just ordered some additional ones, a brand I am not familiar with (Bagail compression cubes) to have some various sizes.
I bought a set of bagail brand compression cubes as they were reasonably priced, had a large which I needed and have thicker fabric. I am very pleased with them.
We used to use 1 and 2 gallon zip-lock bags initially for packing but found out that they bulge in center and are thin on the ends, so they don’t stack efficiently in the suitcase. The beauty of packing cubes is that once filled they keep their rectangular shape and stack, puzzle-like beautifully in the suitcase.
I got a really nice set new at a Goodwill (!). Part mesh, to breathe and see in. 7 pcs, 2 each of 3 sizes plus a shoe/laundry bag. Only complaint is they are all the same color, I’d prefer to be able to tell right away what is what by the color.
I love them for long trips where we move around a lot - I “unpack” by taking out the cubes but leave my stuff inside them. Short trips they can be helpful. Long trips to a single destination I don’t bother, I’m unpacking into a closet/dresser anyway.