Tutorials missing 3dm files

Why is it that tutorials produced by McNeel and others (to help one understand the features of Rhino) rarely include a link (for download) to the model files that they are using in the tutorial? … It can take additional minutes or even hours to build the model so that I can follow along at home, to get a better understanding of the tutorial procedure and Rhino…

Rhino is a very complex application, and any effort to make it easier to understand via the enhancement of tutorials to include the 3dm files would be appreciated.

have you checked help>learn rhino inside rhino itself? There are lev1 and lev 2 manuals and the files that go with those manuals-