Its an essential and required component of many north american festivals. Artistes are expected to participate in on stage and unrehearsed sessions with other artistes. At Edmonton and Canmore last year, I got to play with a huge range of folks that one would otherwise never get to interact with. Madagascar Slim (Fantastic!!),K'Naan, Bob Brozman, The Duhks, Chip Taylor and Carrie Rodrigues, Jez Lowe. Sadly not the Neville Brothers. Also at Folk South wests easter workshops in Bath about four years ago, Myself, Rob Harbron, Tim Laycock and Gina Lafaux had such a good session we came within a ace of forming a band. Still like to do it one day! I imagine that a good regular session crew would make for a great nights entertainment in a club or festival without turning it into a concert. Great idea.