The UK folks seem very well organized when it comes to doing sessions--

We have perhaps too many genres to choose from(Blues, Bluegrass, Old Timey, Jug Band, Hawaiian, Rockabilly, and nine kinds of jazz) and often have trouble getting a quorum--When you do, one of two things happens:

1) Someone knows of a gig, and half the session turns into a band while the other half wander off with hurt feelings

2) The two people who have been coordinating everything suddenly leave to start a drumming circle.

Excepting, of course, if it is a Chanty sing;-)