While a traditional cordelette is about 16 feet of 7mm cord tied into one big loop, many more experienced climbers (if they carry one at all) prefer to leave it untied, known in some circles as an “open” cordelette.
Why use an open cordelette? It’s more versatile.
You can tie the ends together quickly in a big loop if you need it, with a simple flat overhand bend. (That’s right, no double fisherman’s knot required.) It’s fast to tie and easy to untie when you’re done compared to many other knots.
You can tie small loops in either end to make a ”bunny ears” cordelette. This can be handy when the gear is far apart, or you need to sling a big tree or boulder. Just tie a small overhand loop near the ends.
And, you can make an multi point anchor by not really tying any knots at all at least until the master point. Here's one way to do it. It's a little hard to explain in words, so check out the video below.
And here's a second way.
Place three pieces of gear, or in this case, three bolts. At least 2 feet from one end of the cord, tie a clove hitch and clip it to the left bolt. At least 2 feet from the other end of the cord, tie another clove hitch, and clip it to the right bolt. Then, take the approximate middle of the cord and clip it to the middle bolt.
Clip a locking carabiner through the two “U” shaped strands in the middle.
Tie an overhand knot to make the master point. Done!
There is no redundant shelf on this anchor. The loop that goes from the masterpoint knot to the middle bolt is probably okay for clipping a backpack, but not for belaying.
This anchor is easily adjustable. If the pieces are far apart, or farther away from you, tie the clove hitch near the end of the cord. If, like in this case, the pieces are very close together, you can tie a clove hitch with longer tails, making a more compact master point.
Hey, don't take my word for it. Here's a short (31 seconds!) video by expert climber Hans Florine (multiple speed climb record holder on The Nose on El Capitan, among other things) showing this technique.