[Yoda]

Working on acc#3 and have concerns over my grip. It looks spot on like the pic in 10-2-B, but like it appears in that pic, the back of the left hand looks about 10°-15° stronger than pure vertical.

So with a dual horizontal hinge, the toe points up at the follow-through parallel, but of course left wrist again is leaning that 10°-15° clockwise.

Am I being too exact, have I misunderstood, or might this hinder my progress?

Great 'real world' post, stebboko. I'm with you!

Remember, at Impact, per 7-2 (#3), both the back of the Left Hand and the Clubhead Lag Pressure Point (#3) face down the Angle of Approach (to the right of Target).

Hence your "10 to 15 degrees stronger than pure vertical" is not a true 'Turn'. Instead, it is simply the Vertical Left Wrist in combination with the natural Arm alignment as it inclines toward a Ball that is located Up-Plane (and prior to Low Point).

Sorry, but this is a whole lot easier to demonstrate than to explain in words.