All prone. But there is such a competition - for more youthful contestants ( it was not held at this meeting). Not a suitable activity for Grandpa! For me, shooting in the kneeling position would count as "cruel and unusual punishment". I have even worked out how to clean my BPCRs without getting out of the prone position. Creative laziness is a skill you just have to develop as you get older!
But seriously, I observed that many other competitors were shooting in a manner that could be described as hectic. Self-loading rifles encourage shooters to be far too quick in taking the next shot.
The "secret of my success" - if there was one - was to take every shot as carefully as if I had been shooting a 22 match rifle. 60 shots for score in one session - it is very easy to get sloppy towards the end.