To label work such at hurdle mobility drills, mini band series, etc. as “ancillary work” is a misrepresentation of what that work is and what needs to be done. It is not ancillary, it is essential work, a component of any sound training program.
It is basic and remedial designed to address each athlete individual needs. It is most effective when woven or threaded through the fabric of the actual training sessions. This type of work can be excellent to lead into or lead out of a particular segment of training or to transition between segments. It is integral work.