Are you looking for a shortcut to paint miniatures faster? A trick for painting miniatures quickly is to use the dipping method. A well-painted miniature has good contrast. Using a good “dip” shade solution is an easy way to shade models.
You can find a variety of methods in an online search for dipping miniatures or hydro dipping approaches. Almost all of them work, too! Aside from a few limitations, I think using the Army Painter Quickshade dipping method is one of the best ways to speed paint a lot models.