I think anything can be used as an ancillary practice, if you think about it.
Last night, in my swing dance class, I had a revelation. There weren't enough men, and I knew the woman's part in my sleep. so I practiced learning how to lead. What an eye opener! Some of the women I danced with had arms like wet noodles and were so poorly connected to themselves that they couldn't be led anywhere. It made me realize that being a follower is like being uke, and how critical connection is, in both dance and Aikido.
I like out of the blue lessons like that. I tried Zazen, but i've got ants in my pants.