The giant Salmonflies of the Western mountains are legendary for their proclivity to elicit consistent dry-fly action and ferocious strikes.
With those bigger flies I find it easier to cast if you slow everything down. When I first started out it seemed to take a year before the loop would open and the rod load. If you try to cast too fast you will lose all momentum and end up with a mess at your feet. Over-lining helps keep that energy through the cast, and the cast tends not to collapse as much.