It's very common to do as part of a compiling/deploying step, for shared files like css or js, very rarely done manually (maybe for very very small icons). E.g

It's very common to do as part of a compiling/deploying step, for shared files like css or js, very rarely done manually (maybe for very very small icons). E.g. I use url-loader in webpack to do require('./some_image.png') and that's converted to a data URI if the image is small enough (otherwise I get a regular URI). The output is a .js file shared among all pages of the site.