Only One Anaerobic Run Per Week

I got very sore from the anaerobic hill repeats this week. I had planned on running a anaerobic tempo on Thu, my second hard day of the week, but ran 2 mi at or near my threshold, 139 b/m. This is week 5 of X-C training so I really wanted to have a solid hill workout. My heart rate was 165 at the end of the 5th repeat, the best measure of the stress from the workout. I do not use the last repeat because I slack off on the first and last. I did not feel I had recovered enough from the hill repeats to go all out again two days later. Besides, I want to recover some more before my 2 hr long run on Sat. I learned two things this week: First, hill repeats are very stressful and second, I cannot do two anaerobic workouts two days apart. So I will make the second hard day into a threshold run for the rest of the year. I am so impressed with the hill repeats that I am going to continue doing them and not 400 or 800 m flats. The hill I use is a pain to get to. I have to run .5 mi along a busy state highway to get there. But it's a great hill close to my house. It's steep, always plowed, it faces South so the sun melts ice, has very little residential traffic and is 90 seconds long.