Just remember Ginger: NTWs do not show in a fecal because they don’t live there. They reside in soft tissue, joints and ligaments.
I use Quest and Quest Plus, too, as part of my rotation - yet here in the South AKA Parasite Heaven/Land of the Gnat, my horses still get the itchi/scaly/scruffies because of the NTW microfilia emerging. When they show their nastiness, I doa DD of Equimax right away. Then resume my normal deworming rotation program.