The examples given are completely representative of the sorts of changes you can make to reduce size, and frankly fairly representative of the sorts of compression ratio improvements you’ll get (though for some types of things you can definitely do way better). When talking about optimisation for gzip, you are mostly talking about 1–2% over general uncompressed byte count minification. And in practice a lot of your minification is of small things, e.g. SVG icons in an app or site—they’re easier to minify because of their reduced scope.