How should you use it? Black Diamond spells it out pretty clearly on their website:

A sewn pocket daisy chain like this has been a part of climbing for decades. It's a tempting piece of gear to use for many things, especially for new climbers. Look at all those handy pockets! You could use that for all kinds of stuff, right? How about I use it to build a top rope anchor, or maybe I can clip in to the anchor with that along with the rope?

You can probably get away with many of these uses, but please don't. These are designed for body weight, aid climbing only (usually for connecting your harness to your ascenders when cleaning, or to your aid ladders when leading).

As Black Diamond says: a sewn loop daisy like this should not be used as part of the belay or anchor system.

Climbers who use these for other applications may not be aware of their primary limitation: While if it's loaded end-to-end it's rated as a full strength sling over 20 kN, the stitching that separates the pockets is only rated to a maximum of 3 kN. If you clip the pockets wrong and the stitching blows, the carabiner can come completely off the daisy, yikes!

Now, this is old news to many climbers. But as I recently discovered, not everyone has got the message (details below), so it bears repeating.

It’s okay to use these as a personal bodyweight tether, as long as you know the drawbacks. There are a couple of acceptable ways to set this up. There’s also one way that's definitely not recommended, and that’s clipping the end loop and any other single pocket with one carabiner.

(And, if you're wondering about girth hitching to the belay loop instead of your tie in points, it's okay to do that.)

Let's look at a few different ways to use this as a personal tether, first the wrong way and then two acceptable ways. For this to completely fail as shown, you would have to have an epic load that breaks the stitching on about 7 pockets. Highly unlikely, but still not best practice.

The next two ways are fine: gold carabiner in the end pocket, and blue carabiner in any intermediate pocket. If the stitching were to fail in the pocket clipped by the blue carabiner, you would simply move to the next pocket with no chance of becoming completely unclipped. Another way to think about it: you need two locking carabiners to stay safe, unless the daisy is completely extended.

Black Diamond has some nice diagrams on their website. It's tempting to adjust the daisy length like in illustration #2, but that can have a very bad outcome, as we’ll see below in a couple of videos. Illustration #3 should be pretty obvious: if that stitching fails the carabiner is completely off, as in illustration #4.

Let's have a closer look at illustration #2. What's the problem with that, you might think? If the daisy takes a big load and the stitching in a couple of pockets were to fail, you're still clipped into the end pocket, right? Well, guess what, it can fail, and even when you watch it happen slowly it still looks like a sleight of hand, rope magic trick.

Now, if your daisy has a twist in it, then your anchor will not fail. But the twist is very subtle, hard to see and not something you want to rely on. It’s tricky to describe this, but if you want to play around with this, you can replicate it with a sewn runner and some masking tape.

But, daisy chains can be misused in other ways as well. I was recently at a local top rope crag in Oregon, and right next to me some climbers had set up a top rope anchor with two sewn pocket daisy chains. Each daisy was clipped to a solid bolt and extended over a cliff edge. One daisy was fine, clipped only in the ends. But the bolt end of the second daisy was clipped into a pocket and the end loop, to shorten it and better distribute the load, in theory. 

The top rope anchor my neighbors rigged looked about like this:

At first glance, this might look okay. Two sewn daisies, locking carabiners everywhere, bomber bolts at the top, nice load distribution, small angle, fully redundant . . . good to go, right? Well, not quite.

Close up of the left anchor. If the sewn pockets were to fail under a sudden load, the carabiner might completely unclip from the daisy.

Here's another variation, this time using a single daisy chain for a top rope anchor. Please don't do this either.

And, one more variation. I think you get the idea. Don't use a daisy chain as a top rope anchor.

Now realistically, a failure here is VERY unlikely when top roping, when the maximum load your anchor is likely to see is around 3 kN. And, even if the stitching on the yellow daisy were to blow out on one pocket, you would drop to the next pocket and then the load would probably transfer to the purple daisy, and everything would be okay and you'd have a great story to tell.

But, having said that, we can all agree that using gear correctly whenever possible is the best practice. Please don't use a sewn pocket daisy chain for building a top rope anchor, and please don't clip the end loop and any other pocket with the same carabiner.

If you want to see daisy pockets popping one by one in a break test, check out this great video from the Italian Alpine Club, forward it to about 13:20 and 22:10.

When I started climbing wayback-when, daisychains like this were very popular to use as sport climbing tethers for anchor cleaning. Fortunately this practice has pretty much faded into oblivion, but like I saw at the cliff recently, not everyone has got the message yet. Please, if you see anyone using equipment in a potentially dangerous way, consider giving them a discreet and polite reminder of the proper use. 

Maybe a better question to ask yourself is why use a daisy chain at all? If you’re aid climbing, most climbers find an adjustable daisy is a better option. For most trad and sport leading, there may not be much reason to have a daisy /PAS / lanyard on your harness at all. When you’re cleaning sport anchors or rappelling, a simple sling works fine in almost all circumstances for a tether to the anchor.

But, if you happen to have a sewn daisy like this in the bottom of your gear box, there are a couple of things they are good for. One, they make a pretty good over the shoulder gear sling, and two, for big wall climbers, they can help you organize your vertical camping spot.

These inherent problems with sewn pocket daisy chains prompted the invention of tethers like the Metolius PAS (Personal Anchor System) or the Sterling Chain Reaction. These are made of individual loops that are each rated to 20+ kN, so there's no more concern with the stitching breaking between pockets. Some climbers find these bulky and a little awkward to use, other people like them a lot. Give it a try and make up your own mind.

Below: Sterling Chain Reactor (top) and Metolius PAS