Brahms believed that there was no need to publish absolutely everything that Schubert ever wrote.
Rather, I believe that it is very good, if, with the aid of his songs, we can be reminded, among other things, of the social conditions under which Schubert had to work.
I believe Schubert had many different methods for familiarizing himself with a poem: reading it aloud and silently, always thinking up new ideas about it, first letting various things knock around inside his head, until he finally decides what to do.