Depends on how many and how long.  If you do a mile-and-a-half warmup and cooldown, plus 8 eighth-mile hill repeats, that's 5 miles total.  I have alternated intervals, tempo and hills, doing two each week, so over three weeks you do two of each workout: week 1 intervals & tempo, week 2 hills & intervals, week 3 tempo &hills.  Others recommend doing hills during early phases of the training cycle, over the winter for instance.  Then switch to intervals when you get into more specific training for your target race.

Len

I'm alternating hill repeats and intervals once a week so each month I get 2 of each plus one day a week of fartleks or tempo.

achtungbaby wrote:

I tried the hill repeats (10x) tonight by jamming it in the middle of my easy run, so I basically had a longer warmup and cool down.  The result was the opposite of easy...!

 

Thanks again!

Ha Ha!

You need the easy days to recover from the more intense days. Hill repeats are definitely intense.