In reply to iamaclimber: When UK Mountaineering Instructors are tested on problem solving and improvised rescue scenarios, the expectation is that they can cope in any situation with no more than three prusik loops in addition to a normal rack.
That said, I generally carry 2x short prusiks and 1x Tibloc as there are a few situations where I would like the extra efficiency of the Tibloc. Some equipment can easily be mis-used and Tiblocs unfortunately fall into this category. When loaded gradually there is negligible chance of rope damage but this requires care in use, including when ascending and situations with high shock loads need to be avoided.
A couple of final points:
- Mammut Contact 8mm slings are TEN times more expensive than 5mm prusik loops. I therefore carry slings to use as slings, and prusiks to use a prusiks. Saving the 19 grammes which each prusik loop weighs, does not seem a sensible trade-off against the risk of damaging my expensive slings.
- I also normally carry a longer un-knotted length (c.5metres) of 5mm cord and a knife. The tat is invariably used for abseil anchors, but it means additional prusiks can be made easily, if needed.
HTH