When I joined GE 10 years ago, Six Sigma was on the way out. There was a brief time period, a few years ago, at the end of Immelt's era IIRC, when the Lean Startup seemed to be the new favorite methodology, but I have not seen it really used in projects, most people still don't know what a MVP is.
More recently, Larry Culp seems to want to focus more on Lean (which is already heavily used in manufacturing across GE).
Take that with a pinch of salt, since GE is still rather big, experiences may vary.
