Participants sat in a circular formation during the meeting.
Participants sat in a circle during the meeting.
I can’t think of a situation in which a “circular formation” can’t be equally effectively described simply as a “circle.” If any readers can think of a context in which it’s better to write “circular formation,” please let me know!
When my students cannot detect the problem in this conciseness example, I ask them to draw a circular formation on the board. The answer comes to them when they realise they’ve drawn a circle.