For my NPPL navigation skills test I just asked the examiner if it was OK to skip the briefing. The reply was oh god, yes please !
I did ask her to test the brakes when we were on the taxiway though, which she did.
During take off the door on the C-150 did open but I just ignored it until I had some time to slam it shut. Thankfully, the seat didn't slide back that day.
I suppose the important thing is to make sure you don't just ignore the briefing, but I would imagine most examiners would let you skip it.