I'm wondering if anyone has any personal experience of RAID 5 2 drive failure with large drives?

As I understand it, the theory is that with large 1-2TB drives, if one drive fails in the raid set, it needs to rebuild everything so is thus hitting all the other drives very hard, and the chance of another failure goes up, especially if the drives were from the same manufacturing batch. And if you lose another drive, you lose all the data.

This is usually explained after the statement "RAID is not backup" which I agree with.

The theory of this makes sense, and I understand it, but does it really happen?