The End-Game Plot of 3LoD

When dreamt up, the Three Lines of Defense model was a Program ….! Yes it was or you missed the inception.
Now, 3LoD is a scam. Like, here, remembering this and a partial solution here. Just browse around on LinkedIn and other environments, and you’ll see your favourite thought leaders agree [if they aren’t, you have some updating to do in your ‘favourite thought leader’ department, too], and eggheads disagree.

But then, one can return to the Program idea, being one that is Finite. If that is too difficult: It has an end date.

Which means you can do away with at least one line of def [more deaf than def].

The second, I propose.

Almost all of it was intended, and should have been designed, to be in the first line anyway [see the above link on vertical, and here]; the second line being there for initial build and then transfer to the first.
And the rest, can easily be moved to the ‘third’ line.
Not only by using ‘agility’ ‘only’ as here, and here [nice ripoff of your competitors’ ideas …], and here, but also by taking the following into account:

Agile and waterfall style approaches are not competing methodologies; they exist at opposite ends of the production lifecycle.

They are both usually necessary in a large organisation.

Try waterfalling a new product idea, or agiling mass production and you’ll get it.

— Jon Ayre (@EnterprisingA) February 12, 2019

Which, when you think of it, leads to the 3rd Estate doing all these things, resulting in

The third line being the Intelligence Unit on Controls. Like the G2 is in the military. But then, for Controls only, very only the lonely. Running in circles of controls monitoring, at any scales, and recommending improvements [also at any scale which does include risk tooling, control, and management in the 1^st line]

I think I’ll expound on this one a little [a huge little I guess], in a short while. Oh, and in the mean time, don’t forget to update yourself with the latest, clearest thinking on the 1^st line here (again-link).
For now, I’ll leave you with:

[The style of tower you’ll need to lock them up in; Figueres]