I have often wondered if those who are planning or analysing potential caving operations have ever made use of / or found a use for the Q-system ratio Jn/Jr. Ja is also tied to caving potential according to analysis of a big data base of caving data from Potvin et al. by Frazer of CSIRO (pers. comm. 2006). In tunnels and caverns Jn/Jr >/= 6 means almost automatic over-break, and some contractors have used this in claims caused by excessive shotcrete/concrete use, this depending on respectively NMT/NATM approaches to support. I am aware of course that a lot of energy has sometimes to be 'added' to gravity processes in caving when there is insufficient joint continuity. Is there -in this connection -sometimes too much joint continuity and ease of caving?