[kbrkbr]

I am sure that's what you mean, but I think it is important to state it explicitly every now and then:

> Defence in depth means you have more than one security control

that overlap. Having them strictly parallel is not defense in depth (e.g. on one door to the same room a dog, and on a different unconnected door a guard).

[MattPalmer1086]

Yes, fully agree. Should have made that explicit. And also different types of control too.

So you might have a lock on the door, a dog, and a pressure sensor on the floor after it...