Until I read this thread a few weeks ago, I had never heard of packing cubes. It seemed like a good idea so I bought some in miscellaneous sizes to try them.
I've just finished packing for five days away and it took twice as long as usual because, having wodged all my stuff into packing cubes and compressed them, the suitcase wouldn't close! These great, rectangular lumps were far too rigid and unwieldy.
So I reverted to my lifelong habit of folding things loosely and layering them in the case with small items - socks, knickers, chargers, meds etc - just tucked into corners and odd spaces. Wash bag unrolled and draped across the top of it all. Job done.
The packing cubes can go to the charity shop.