jpeg-archive (https://github.com/danielgtaylor/jpeg-archive) may be the better use case images that you don't intend to have downloaded a billion times.

I tried jpeg-compress -c in.jpg out.jpg (-c skips output that is bigger than the original) and got visually good results, lower file sizes, and quick processing. The file size ultimately will be larger the guetzli, but not by that much more and it doesn't take an extremely long time to compress one image.