Currently I'm running 12 400m repeats on a track, with 3 minutes for each repeat: so roughly a minute and a half of recovery between each lap.
What constitutes 'good' quality for these intervals?
eg should I be aiming to hit exactly the same lap time throughout the session, or would that mean that I was going out too easy for the first few?
should I be doing less repeats? Increasing the recovery time between them?
(Currently I'm doing the first 4 in about 1:22, the next four at about 1:30, and the remainder fluctuating between 1:25 and 1:35)