Is there any documentation on this? I ask because frankly, I didn't think that is how OneDrive worked. For one, I don't think OneDrive is technically considered a "backup" tool. Rather I thought it as a file "sync" tool with the primary goal of being able to access the file from different platforms - that is for file sharing. That inherently provides some level of backup capability - unless the file has been modified (or deleted) from a different computer.
Also, Microsoft only provides 5GB of storage - unless users opt for one of paid versions which start at $20/year. Not sure 5GB would provide much "backup" capability.
I have seen several comments about users complaining about Microsoft's use of the word "backup" when referring to this tool.
As for when it syncs, I was under the impression it is done in near real time with Windows Push Notification Services (WNS).
However, I was also under the impression OneDrive could be used for true "backups" if used with 3rd party apps designed for that.
Of course, I might be totally wrong.