I once read in the old Concertina & squeeze box mag, that you needed 8 tunes down cold. To hold a set. Perhaps they were talking about a 45 min. set. Then one of the tunes being "drunken sailor" that can streach for as long as you can stand it. a Then a bit of chatting between tunes, could make the 45 min.

Fadac - The let me introduce my bus driver, man.