It exists in the long fist system a lot. I have trained those moves all my life but have never be able to apply it in sparring. Either my kick can land on my opponent's body, but my fist is too far, or my fist can land on my opponent's body but my leg is not fully extended yet.It might be a jab and a front kick at the same time ...
IMO, this kind of training is for body coordination, flexibility, and balance.