Using the face of a clock is a common way to illustrate casting but it is also very misleading.
The two major ways the angler moves the rod is by rotation of the rod butt and by the stroke path. Lets define what those are. Rod butt rotation is what the clock face is. If we say 10 to 2, that is 4 hours or 1/3 of the 12 hour 360 degrees of the clock face or 120 degrees of rod butt rotation. Way too much in my opinion for a beginner cast.
The other factor is the stroke path. That is the movement of the rod butt handle through space. Rather than just rotating the rod around the butt cap, the rod can move back and forth, up and down, right and left. Whereas the rod butt rotation occurs in a two dimensional space with the base of a rod fixed at a point, the stroke path is the movement of the rod through a 3 dimensional space.
To illustrate the difference, look at this video from Sexy Loops that uses a rod with the rod butt fixed to a table top. The rod is like a flexible clock hand rotating on a clock face. This is exactly the image we give to novice casters. But notice that when the rod butt is fixed, because of the shortening of the chord length of the fly rod as is flexes, every cast MUST be a tailing loop.
Tailing Loops - description and cure
One of the purposes of the stroke path is to move the rod in a convex path, to correct the concave path of the rod tip as the the rod shortens due to its flex.
Why does the stroke of the rod naturally go in a convex path. Fortunately the joints we use to cast with naturally move the hand in a convex path. We cast with the shoulder, elbow, wrist, and sometimes with body rotation. Allow you arm to hang down loose and swing it - the hand swings in a convex arc. Bend your arm at the elbow and do a karate chop - your hand goes in a convex arc. Extend your fingers and flex your wrist in any direction - your finger tips go in an arc. Stick your arms out to the sides lie helicopter blades and rotate your body - your hand go in a convex arc. In fact, almost every hitting sport like tennis, golf, baseball moves the arms in an arc and so does throwing a baseball. So convex movements are natural and concave are unnatural.
The problem with the clock face is that 10 - 2 (120 degrees) or even 10 - 1 (90 degrees) is too great a rod butt rotation for a beginner and it introduces the "fact" that the optimum degree of rotation is fixed for all casts. Accomplished caster know that we vary the rotation depending on the length of line cast.
As we can see in the illustration below the stroke bath and the rod rotation increase as distance increases. The green, red, and blue lines sow the increasing degrees of the arc on the imaginary clock face. So forget 10 to 2 o'clock as the optimum degree of rotation. It is not.
I once read a study on the optimum amount of rod butt rotation for a beginner's cast and if I recall correctly it was well under 90 degrees. Since beginners tend to overdo the rod butt rotation, I use 10 -12 or (60 degrees). For longer casts and for the Lefty Kreh method you lay the rod back and the degree of rod rotation as see as a clock face from above can be almost 180 degrees.
Here is a slow motion video of Lefty making a moderate distance cast indoors. IF is here really hauling line, you would see that he lays the rod back even further and stops even later.
Look a how much he lays the rod back and how far forward he stops in the first part of this video.
Lefty part 2 - YouTube
Casting is dynamic and the stop points, rod angle and and stroke paths change with the distance and air resistance.
What I would recommend is that you STOP trying to make long casts using the Lefty Kreh method. What I do recommend is that you begin by making short casts using the Lefty Kreh method, and then working up to longer casts.
The keys to efficient casting are a SLP of the rod tip, HARD stops (the hammer example) and proper timing of rod tip acceleration.