Well, I don’t know if this is any sort of record, but I successfully formatted a system that was originally 116% full… with lyrics too. 
This would have been possible in Finale, of course, but far more time consuming… and probably never would have looked as good. The beauty of Dorico’s note spacing is that when you give or take space from a rhythmic position, Dorico compensates by borrowing from or lending space to the other rhythmic positions on the system.
But the ace in the hole is that this inverse relationship isn’t simply linear… it seems to borrow space from other rhythm positions based on how tight or wide they already are, like a variable tax bracket or something. The result is much more intelligent spacing than I’d be able to achieve by hand.
I attached a pic below. It’s tight but quite legible.
