HA! I had received new 16-bay chasis and all of the drives needed plus cold spares for each chasis. Set them up and started the RAID-5 init on a Friday. Left them running in the rack over the weekend. Returned on Monday to find multiple drives in each chasis had failed. Even with dedicated one of the 16 drives as a hot swap, the volumes would all have failed in an unrecoverable manner.
All drives were purchased at the same time, and happened to all come from a single batch from the manufacture. The manufacture confirmed this via serial numbers, and admitted they had an issue during production. All drives were replaced and at a larger volume size.
TL;DR: Drives will fail, and manufacturing issues happend. Don't buy all of your drives in an array from the same batch! It will happen. To say it won't is just pure inexeperience.