Partial file sharing is very effective in that regard. I'm not sure if a person necessarily starts from the very beginning of the file to downld. But much more likely if partial file sharing is concerned.

And yes, hosts do drop off with large files toward the end. I saw someone give a good description but can't seem to locate it. And I believe that applies to the idea that since files are not necessarily downlded sequentially, it means the other missing last bits may be spread around.