There are timers set for at least some trials I attend, though I only became aware of it because my husband (who scribes a lot) told me that it is often a thing. Otherwise, I would have never known; it's just not an obvious/jarring thing, at least the way I've seen it done.
That said, while it can be daunting to try to remember the courses I find it really DOES, as with everything agility related, get easier with time/practice. NADAC courses are so flowing it really helps. You're not going to know where the course goes before you walk it, you do need to walk it, but sooner or later you start seeing lines of obstacles, not individual obstacles. That helps both with running and remembering the courses.
