Curious how many Karateka here do this. I first learned Kakie in Goju Ryu, the way we did it orginally made it seem useless to me, and I spent years thinking i'd just purge it from my own syllabus. The version I originaly learned was rote, immobile, disconnected from application, and mainly just tired out your shoulder. Frankly, this is the version I most often see.
Eventually I did a seminar with an Okinawan Kempo practiioner who also was trained in some some "old style" Karate by his father. He put alot of emphasis on push hands drill. It was like the kakie I learned superficially but very functional, and he was able to relate it directly to applications we practiced alongside in a way that made the drill hugely useful, vital even. It very close to what I've seen in Taiji, minus some small mechanical differences. Definitely different from what I've usually seen presented as kakie, more fluid, less prescribed, and directly addresses centerline movement. Since this time I include it in my syallbus, and I notice it gets definite results with students in terms of movement ability, use of tactile sense, posture and centerline awareness. A specialized dril for sure, but useful and open-ended.
Do you do this kind of drill? If so how is it useful to you? Do you have any particular methods you favor?