Expand on it further:
Base phase a few times a week do runs over hilly courses and short hill sprints. For example, Lydiard athletes often did there 22 mile Sunday long run up this one course(I can't recall the name right now) that was really hilly.
The hill phase Lydiard had in mind. I'm not really a big fan of. As I believe you can and should do a little bit of hill bounding throughout the year. As it does wonders to your form and really strengthen the leg muscles that you can't really get from regular lifting. But, steady runs over hilly courses is one of the best/underrated runs one can do, especially if you throw in surges on the uphill sections. Definitely do that kind of run at least once a week during the base phase.