I just follow up on community theme updates and add them manually if their necessary.
Most updates usually are on core files or modules and not theme files.
I usually setup the new theme based on the client design and makes sure that there are no bugs, in most cases the theme don't need any future modification that are bugs related.
If you look at the community theme repo, it has only 87 commits in total and most of them are before it was stable for release, and some of the others commits are not important if you modify the layout and the css.