Long Hollow wrist walk

Question about long hollow wrist walks: this has been the only wrist progression that seems to be slower to strengthen compared to the other wrist walk and while not painful, it rather feels "dicey" or more anxiety-provoking when I'm performing these. Is this common? It's particularly noticeable in the wrist flexion phase of the exercise compared to the wrist extension. Thanks for any explanations. 

P.S. I do not have any prior injuries to the wrists.

Hi Brian, i completely agree with you, the muscles supporting the wrists and fingers flexion are stronger and more developed compared to the extension that is, for evolution, less useful for use. the wrist extension strength takes probably double or triple time compared to flexion in order to be developed in a full range of motion.