You'll get many different views and opinions on this on this one I'm sure!

For me personally, I always set them at the looser end of the range. Why? Because valves clearances close up over time and a tight valve is much more damaging than a loose one, so I like to give a little room for this. Plus, with screw and lock nut adjusters, I always find that no matter how hard you try to hold the screw while you tighten the lock nut, it'll always nip up a fraction further than you had it set.

__________________