As Dave Bryant says, this music is meant to be played at a dancing speed. This can be quite fast, if you are dealing with Irish set-dancers for example, but not stupidly fast.

In fact playing tunes relatively slowly is harder much of the time, because it's more difficult to fake the tricky bits.

Beginners' sessions could be useful I suppose, but talking in terms of "slow jams" puts an emphasis on the wrong things, and feeds into the nonsensical notion that expertise in the music is learning to play it at excessive speed. That's no truer of music than it is of driving.

But one of the most enjoyable and important things about open sessions is the way that musicians of very different levels can play together in a way that brings out the best in them all. The best in musical terms, and the best in the way of courtesy and friendship. So there's a cost to be paid if we split each other up according to musical skill - and playing with more skilled musicians who aren't just showing off all the time can enable people to learn amazingly quickly sometimes.