Well, sessions havent been that standardised by the look of things. The only one I go to regularly, nobody plays any of those tunes listed above, with the exception of the Merry Blacksmith and the High Reel, which someone trots out once in a blue moon if someone vociferously calls for an Irish reel.
   Mind you, I have been to a lot of sessions elsewhere where thse tunes are the satple fare. But why not, eh? Tunes are the common currency of exchange at sessions, and it stands to reason that people will use well known tunes if they are there for the pleasure of playing with other people. It makes more sense that way, it can be a bit wearing if someone comes in a plays whole strings of tunes nobody jknows and arent quick enough to join in at one hearing.
   As a side question, how many times do people play tunes at your sessions? I never think two is enough, four gives a chance to learn them.