Wow, a 1:06 half! You must be a VERY good runner.

For runner with less experience, I'd suggest building more rest into the week. I make sure I get at least 1 day with no workout at all. Ideally 2 consecutive days off, and as I a get closer to my race I'm trying to get 3 days off.

A few things I've learned I'd like to share:
-Any running at all creates a stress on your body. You get stronger during the rest period between stresses not on the days you are creating stress.
-Your body adapts to stress over time, so unless there is variation in your workout your improvement slows down, stops and eventually reverses. Week to week your speed, distance, or stress/recovery ratio needs to be changing (but only play with one variable at a time)
-workout intensity seems to be more important than duration. In the past I would always increase duration and I just kept getting slower and slower. Now my duration is around the same but I'm increasing intensity every week and I see much better results.

Over the last year I've dropped a minute/mile from my pace. Over the past few months I've been going faster every week. I'm finally starting to catch up with people who were so much faster than me. I'm training for a triathlon and I typically have 3-4 run workouts a week.
1 treadmill interval workout right after spinning. Surprisingly this has been a key tool because I go at it HARD and my legs don't feel sore the next day
1 short run immediately after my hard cycling workout.
1 trail run or tempo run. This is key for learning to hold a controlled pace over time.
1 track interval workout. I go so fast here my legs are sore for 3 days or so.

2:30 800's? Dude you are a stud!

I'd like to manage a sub-4 for my 800's. I'm too busy cross training...