Not all webservers support/enable it, so YMMV.
But as long as you're dealing with a known server that does, then gravy!
But as long as you're dealing with a known server that does, then gravy!
Could you provide an example of server that does not?
AFAIK, Range is supported by all major CDNs, so not supporting it in web server would be a death knell for it's real-world adoption.
I would assume this is often because the site in question isn't using Apache etc. to serve a file directly, but is either essentially proxying it to some custom-built file serving service, or a script that processes/authenticates the file in some way, and they just never bothered to implement Range.