I haven't been to any beginners' sessions - I usually learn what I want to learn from the music or by ear and then play them, if I know them competently, at a session. However, it seems to be the norm to put 2 or even 3 tunes into a set - and there are quite a few conventions as to these sets, depending on the locality. "Dennis Murphy's Polka" and "John Ryan's Polka" is a popular pairing, for example.

If you're interested, you can see the local Lewes Favourites here. Much hard work and dedication there on the part of the Lewes Saturday Folk...