Well this discussion died. So I’m hiring a zombie necromancer to revive it.
I think ‘cotton sheeting’ could be an item that has ‘cotton sheet’ charges that are never seen apart from the main item. Like a disposable battery, you would be unable to reload or combine ‘cotton sheeting’. You also wouldn’t be able to unload ‘cotton sheeting’ or split it just by dropping half of it. This would give the fiction that we are dealing with parts of a larger-than-rag sheet of fabric more backing and reduce the confusion about what the point of having it exist is.
A rag is 0.08 kg, while cotton sheet (1) weighs 0.01 kg. Which does mean that it is a useful unit when disassembling or cutting apart clothes that weigh less than 0.08kg.