Hi, PalmStriker and T.D.O:
Im not a Wing Chun practitioner (Im a CLF practitioner, among other things), but I thought Id share. I have been using a similar-sounding hand conditioning method of striking my hands against each other. I actually started doing it on my own years ago. I train the palm heels, palm edges, flat palms (for power slaps), hammer fists, and hammer fists to palm heels. Then I support my weight on my first two (index and middle finger) knuckles (similar to a push-up position, but without doing push-ups) on a linoleum floor for a couple minutes, to condition the foreknuckles and wrist alignment for straight punches. Been doing this for quite some time. Even though its far less extreme than many methods, I still apply jow before and after, and carefully massage, stretch, and shake out my hands, and do arm swings afterwards.
For my forearms, I use an Iron Arm Conditioning Hammer on the ulnar and radial (boney) sides, as well as on the muscle/back area of the forearms. Followed by hitting my forearms against each other (using light to moderate force). Also some slapping/palm heels to the forearm muscles. Again, I use jow for that, too. The only problem with the Iron Arm conditioning hammer is that it makes a loud clacking sound; not good if you share space with or around others. I dont, so its not a problem for me.
These methods work well. I practice them about 4 days/week.
Two days/week, I also train grip strength. I use Heavy Grips. Not too much and not too crazy. Im currently working on the 200-pound unit. I have others that are higher (they increase by 50 pound increments), but Im not in a hurry to get there, and dont want to strain or injure my hands, or develop tendinitis. I warm up for that by squeezing tennis balls and even squeezing my hands together as hard as possible for 30-second sets. You dont want to jump into using the Heavy Grip units without warming your hands up first, and only do low reps.
Then a couple days a week I strike a BOB dummy.
My training isnt nearly as much as what I did in younger years, but at 57, I would rather be able to do some training than none at all. Of course, the above isnt all of what I do, only my own hand/forearm conditioning methods.