When using a download manager to download a large file, what is the best strategy to adopt? Should I split into several streams, or just one? If I have several files to download, should I download them in parallell, or one at a time?
If no throttling is occuring along the network connection, then stick to 1 download at a time.
If you are a home user, either dialup or broadband, then the speed at your end is set by the hardware and the ISP. Trying to download simultaneously justs adds extra overhead that hurts rather than helps (at your end).
Doing parallel downloads might help if the site at the other end has lots of total capacity but allocates a limited amount per connection. E.g., my ISP’s newsserver has a restricted bandwith of about half my broadband connection speed. So running two connections at a time helps. Running a third is counterproductive.