I have been following GB for about 5 years and doing wrist work pretty much 2 times a week before workouts. My wrist strength seems to have improved over this time but I have not gained much mobility in wrist flexion. I think I have pretty good mobility in most directions but I can barely get beyond a shoulders over wrists position when stretching in a pushup style position with fingers pointing forwards and palms on the ground.
I have actually found that when I have my arm out straight in front of me and try to flex my wrist so my fingers point to the sky that I can only get to about 50 degrees. My mum seems to have the same problem so could this just be a hereditary thing? It makes things like the wall handstand with wrists close to wall quite painful.