Everyone has a different combination of power and speed in different parts of the body. That might change over time too. Some combinations might mean different body positions at the rip for different persons give the best D for each individual. So experimentation might be needed. The longer you accelerate the faster the disc should leave. Not everyone has enough muscles to accelerate hard from when the plant step touches the ground.
For more squared to the target body orientation a lower stance with a steeper squat from the knees helps and pushing with the left leg forward and back with the right leg from a relatively slow speed into the plant step. Not running pell mell unless you have pro athlete level muscle power. Even that may not suffice. It is pretty essential to brace the right leg when the heel touches the ground in the plant step. When to lighten up with the leg muscles to start the heel pivot depends on how fast the arm is moving where. Another case of experimentation is needed. Some might get best results before the right pec position, some at it and some after it. The later the heel pivot starts the quicker the acceleration of the rotation via the lever of the right shoulder and the arm is. Pivot too late and the end speed might be less than maximum.
Where the max speed and hard(est?) acceleration combo gives the best distance might vary from person to person. I don't know if any studies have been conducted on that. I imagine that the exit speed counts the most so one might start experimentation by trying to maximize the exit speed and trying to get as much acceleration before the best rip speed acceleration points are. Those are when to release the leg bracing and when to accelerate the arm the fastest.
The heel pivot and the forearm straightening and possible (beneficial) movement of the whole arm to the right from the shoulder socket all change the direction your body mass is moving. The disc pivots between the fingers going back to front pretty much while the body and the arm are going right. Even when you stop the elbow and the wrist thanks to the heel pivot and the hips twisting and shoulders turning. Those generate a lot of power possibly more than the arm alone.
With enough acceleration the weight of the disc should be noticeable at least once the elbow starts to straighten. Pinching can be started pretty late possibly even after the feel of the weight happens. The nasty thing about that is that the sensation needs to travel to the brain and get processed and the command to pinch needs to travel to the fingers. It takes time and the arm has moved a lot. It is possible that you have pinched too late and that reduces your consistency. I'd experiment with earlier pinching times to make sure that you don't get slips from sometimes pinching too late.
Catapulting is a good word. It happens when the direction of the arm movement changes and the disc pivot really accelerates. Even harder than has happened before that. The tighter the corner and more abrupt the direction change of the arm movement the faster the disc pivots=snaps out like a bat out of catapult

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.