I've only ever used this once. We had a client who wanted to move from our hosted platform to their own infrastructure. Rather than wait on courier to pick up and ship a drive with their backup, they requested it be done via FTP.
If I recall, it was about 50GB in total, so I made 10 x 5GB files and had them pull it all together back on their end.
I still say getting a courier would have been less pain than sitting at home from 11pm copying the files on one by one because they only had about 8GB free on the FTP site! They were a US company and they could only do this in the evening for some reason!