In reply to needvert:
> I have a short one, enough for a 6 wrap. Then I have much longer one, long enough to make releasable through a munter mule.
I do as needvert. I carry one long and one short.
One long 6mm loop that I also use to attach the chalkbag around my waist. I can move the chalkbag out of my way in chimneys. The long loop can be used for Prusik, load releasable knot, abseil tat or extending the abseil plus a leash ( ). I attach it around my waist using a sheet bend.
Another short 6mm loop clipped or girth hitched to my harness. I use this to autoblock the abseil or as a short prusik which I can extend with slings, if necessary. I've used it doubled over as a short draw in a pinch.
Yes, I've practiced using this to prusik but never had to use it in anger -- so far.