The thing with Sage is that, wherever you start your project, that’s your starter theme. Unless you’re planning a big project to carefully integrate new Sage features into your (by Sage’s intent) heavily customized theme in the future, whatever happens after you
git clone (or
composer create project) doesn’t matter unless you want it to.
I’ve almost never gone back and integrated changes from newer Sage commits once I start a project unless it’s a fix for newer versions of npm breaking my gulp or yarn process. If I did that I would need three more developers just focused on keeping our old sites updated with Sage changes.