When you play at an open jam session, you knw there will be other players and singers wanting to contribute, you know the 'performance' you contribute will be modified to suit the group of contributors, you accept that some will help and some will hinder - sometimes you won't recongnize your own arrangement. If you want performance enhancement only, you need to consider private session, or rehearsal, with those players you select.

Also each session has their own rules. The best have very few! Mutual respect for one another's contribution is the key to success. Some inadvertant toe stepping may occur, but over all, if the circle attendees are well balanced, considerate adults, these instances will be few and far between.