It depends what you're going to do with the head. I'm deathly scared of handling a head with valves open. I also don't have a long enough XZN bit to remove the head bolts covered by the cam towers. That's why the cam is the first thing I remove.

Next is a suitable place to work on the head. The block makes an excellent work bench to remove the turbo and exhaust manifold. I'd have to fabricate a jig to hold the head with valves open to a work bench otherwise. The nuts and bolts holding the turbo to the manifold are on there but good. You'd flip the engine on an engine stand levering the fasteners you can't get to with an impact wrench.

A personal reason is I have two skinny arms and no hoist. I have to work within the limits of what I can lift. Dave has German elves who work on his cars and keep everything clean while he sleeps so I don't know his motivations but I suspect the cam came off for access to the valve stem seals.

If all you're going to do is give the head mating surface a cursory cleaning, I suppose you can leave the manifold and turbo attached. Then you have to worry about head gasket debris getting into the ports through open valves. That's not for me.

Sixto
87 300D