By natural trails I mean non-trail centre, I appreciate most trails are man made to one degree or another!
Example: riding at the weekend on a very tricky bridleway descent in the Lakes. Some sections are pretty much unrideable (unless you're Hans Rey) but could be "ammended" to be less unrideable by shifting rocks around.
My personal view tends to be ride it as you find it and if you can't ride it that's your problem. But sometimes I am tempted to start "fixing".
What's your view?