I think the point of that passage is that if the GM ever says, “Everybody test at the same time for this one thing”, it only takes one Turn, and not one for each Test.
As I understand it, a Health test to avoid a trap still takes up a Turn, but if everybody in the room has to make that test, its still only takes up one Turn, total.
Works for me. I hadn’t even considered a test to avoid a trap taking a turn before, so glad I caught that section this time around. Don’t wanna rob my players of losing those precious turns >:D