The other day, I have listened to a radio program where an ENT doctor was talking about sensory hearing loss. He said, in that condition, the patient could not hear but also understand what others talked to him/her. Not only the inner ear and auditory nerve but also higher brain center responsible for understanding are often disturbed.
For such a patient, we should not speak slowly but should emphasize each word with sufficient spaces between them, as the doctor said. That wider spaces are of much more help to the handicapped people. This means simply that we are not listening each character but meaning of each words which eventually leads us to the whole meaning of a sentence.
I believe it is also the case with CW reception. We are taking what the sendes says by taking meaning of each words, of course, not by each character or whole sentence. Longer the spaces between words are, easier we could take its meaning, that is, what the sender says. This space between words is determined in the relation with the space between characters. If the latter is too long, it is often difficult to take each word as it is. The latter should be as short as possible while the former should be long. It helps us to read sentences sent with CW.
Aesthetically, such code sending sounds more favorable as well as more beautiful than equally spaced codes. I could remember an example of beautiful code sender. It is Rod K5BGB. It was a pleasure for me to listen to him making pretty good spces between words with rather short ones between characters. It was a functionally as well as aesthetically excellent code sending. Unfortunately, such an operator is rarely heard nowadays.