We get this question a lot from clients since we have a clear purpose/intensity behind our main training types (Easy, Threshold, Marathon, Interval, Repetition, Fast Reps) but not for hill repeats. We see hill training as Repetition work but with added resistance. Just like Reps, hill repeats help improve speed and economy.
In general, you should run hills at the same effort as Reps (current 1-mile race pace). They should not be sprints so you want to focus on running with good mechanics and make sure you’re not tightening up a lot near the top of the hill. Run hills fast but strong and relaxed throughout. Our concern with hills is always regarding the repeated downhill running between the work portion. Make sure to be soft/quiet on your feet running down the hill to reduce impact and ensure that you are taking enough time so you’re fully recovered between each.