QC LAB: EXTENDING A CAM SLING

The sling-on-sling method of extending a cam sling does save the use of a biner but does it reduce the ultimate strength of the system?

When I rack for a multi-pitch trad climb, I rack like this:

Cams (with a biner on each cam), set of Stoppers on my harness
Quickdraws and a few spare biners on my harness
Over-the-shoulder runners with one biner on each—over my shoulder (well duh...)

If I need to place a cam, I grab one, place it, clip it and go.

I saw him fiddling at all of these cam placements and was wondering what in the world was going on up there—he's taking forever farting around with gear—maybe it's because he's so strong he doesn't get it—but for me, I need to place the piece and keep moving before I flame out. So as I'm seconding his pitches and having to deal with this unfamiliar conglomeration of slings on slings on cams, etc—I'm wondering:

Why is he doing this? and
How much does this affect the strength?
And, I am getting pumped out of my mind.

I mean nylon on nylon or Spectra on Spectra, etc—sounds like bad juju to me—and I'm not talking about girth hitching anything here—just looping it through.

I get to the belay and ask my partner what's up with the method—and then it all clicks—ahhhh "old school alpinist," light is right, save a biner, etc, etc—and old habits are hard to break. Regardless, I got back from the weekend, explained the situation to the crew in the QA lab and we proceeded to do a few quick tests.

The Tests

We slung some 8 mm Spectra through a typical cam sling and did a few pulls in the tensile tester and a few drops in the drop tower. We compared the results to a cam sling only.