WLD
Yes that does sound a bit daft doesn't it - I was in the throes of a sort of aggresive nostalgia and liable to exaggerate. What I meant was that I only lead maybe three (OK it may be more) because of the long gaps while people decide what to play (don't they know it's their turn next??) so the circle is circumnavigated only 2 or 3 times.
Now to qualify my second sentence - the word "lead" - I don't mean to imply that I want to lead tunes or indeed a session, music should be a shared experience with a mutual direction. However in the tunearound scenario everyone is expected to lead in turn and this puts added pressure on the "leaders" and does, in my experience, lead to excessive nerves and a less than satisfactory rendering of a tune.
If a tune is thought of as a template then surely it is better for a less experienced musician to try to fit to that template rather than the rest of the room having to diverge from that template to accommodate a beginner's/learner's hesitant rendition. It's how I learnt anyway - noodling behind other players until I could join in with confidence.

I hope none of this sounds arrogant - I appreciate that everybody has to learn and there should absolutely be occasions, possibly in private, when this can happen. But if it's a "session" and open to Joe Public in the bar or wherever I feel that the tunearound will look and sound totally false and stilted.
Martin