I would assume that if you have a toolbox with only a small number of tools, you would spend some of your time using that set of tools to make other tools that extend your abilities.

I know that many developers in earlier times, before the internet, when programming languages were more limited and access to library repositories was not possible most experienced programmers built up their own libraries of functions that they would use and add to as required.

These days, we still have these extensions to the languages, but they are shared in repos and are called shared libraries or frameworks.