Keep in mind that there has been a tendency throughout the 20th Century to play traditional music faster than ever before. This is not necessarily a bad thing, but it does mean that the average musician doesn't need to imitate the professional in order to be true to the music.

Of course, some pieces should be played fast, but not as many as we think.

What you should do is set a pace so that people are having fun. At a session, this means that everyone is getting to play, and not just the stars with the most expensive instruments. Also, the notes should be defined, not just slurred over at top speed. One should, for example, be able to tell the difference between major and minor.

At a dance, the music must be fast enough for the dancers, but not so fast that only experienced dancers aged 20-40 are on the floor.

Also, a session should not go on at the same tempo all night. That gets old for the other guests who are not playing.