It's not about the process taking less time (even though aiming to reduce that is a valid approach, which is usually tackled by using ssd/flash and not over-pro

It's not about the process taking less time (even though aiming to reduce that is a valid approach, which is usually tackled by using ssd/flash and not over-provisioning). It's much more about being able to handle a second disk failure during rebuild. With raid 5, if that happens, you are in a world of hurt (think 3k fees to send raid to data recovery place). I've learnt all this the hard way.