Reminds me of https://www.sakugabooru.com/, a booru that is (as I understand it) designed as a reference for anime animators
Especially https://www.sakugabooru.com/post/show/147316
Apparently the animator eschewed keyframes entirely, opting to "just do it correctly" frame by frame. I haven't seen weight conveyed quite like like that.
somewhat NSFW - https://ffound.tumblr.com/archive