GG throws 700'+ with a three finger grip but says that sometimes he uses just two. The colder it gets the more fingers you need on the disc to avoid early slips and grippy material. Blake hinted at but did not fully explain that different grips give different wrist movement ranges and fluidity=different snap speed and acceleration. There is probably variation across people according to arm, hand and finger strength and limberness. I throw the farthest with, according to radar 3 MPH average faster, two finger grip than three fingers. Which is a little looser in the muscles than four fingers which can be learned to be loose over time. At least if you're limber. The more muscle power you have the looser you can keep the arm so the more fingers you can keep on the disc. I suggest lifting weights, using grippers, finger push and pull ups, cable work etc.
Flat shots need running on the center line of the tee and planting each step on the center line. Anhyzer needs running from rear right to front left with the plant step hitting the ground to the left of the line you're running on. Hyzer is the mirror of that.