When I work in Flash, I work with 3 different types of movies:
Experiments: I just scribble, draw, and try out different settings. Not trying to actually create a finished project, frees me to try anything and everything and learn about the different possibilities that are available.
Resources: I may open a file and draw lots of different flowers. I may need a few flowers in a project I'm working on. Instead of creating the flowers directly in my project, I draw a bunch of flowers and select a few for the project I'm working on. Instead of discarding the page full of flowers , I save this file as flowers.fla in a folder called resources. Later, when I need flowers for another project, I can open this file and pick the ones I want, or draw some new ones to add to the file. I have similar files for butterflies, birds, trees, clouds, etc. These files can save a lot of time later.
Finished projects: these are the files that I will eventually publish. But they may also serve as a resource later when I borrow a house or tree to use in another project.
You learn something different with each of these types of movies.