Instead of downloading large files in one whole big fat fallible download, try chunking it, and instead downloading smaller chunks, that get verified and held by the client, even when the download as a whole fails. This means less retries and both less bandwidth usage for both the company as well as the client's side, while improving quality. Less retries, less angry people that have to rely on lousy/fallible connections.
I'd say about 1GB to 4GB chunks for maximum file part sizes.
It should not matter how the file as a whole would look or how large it is, just chunk it and retain it, piece by piece and re-assamble as the whole file after download finally yet finishes.
It's better economically for both Steam as a company as well as the people downloading their software.