Given Tolkien's druthers, he'd have kept it all in a private repository, working on branch after branch, cherry-picking changes strung like a Christmas tree.
What he really wanted to release was The Silmarillion, but they passed. It included a long but incomplete verse version of Beren and Luthien, which utterly baffled the readers. The publisher demanded a Hobbit sequel -- which already included a bunch of random stuff from The Silmarillion, but mostly just a few inconsistent fragments.
So he wrote The Lord of the Rings, and despite himself, managed to actually get it released. All the while he kept tinkering with his masterpiece, never releasing it at all. Some other developer (his son) finally cobbled something together after he died -- mostly by reverting to branches that were decades behind the HEAD.
He was very, very, very unproductive. But he sure made a lot of commits -- and then reverted them.
Tolkien was an academic and didn't approach this in the same way a professional writer would today.
Sounds like a good framework for productivity.