Quick question: I recently did a comfortably hard, not all out, workout. I did 1200,800,400,400,800,1200
3:47, 2:34, 73, 70, 2:33, 3:43
rest was averaged the time of the previous interval x 1.5, although that was a little less on the longer rests and a little more on the shorter ones.
Guess what I could run for mile/2mile based off this, and then I will tell my actual PR I set recently.