Control the pace. Always.
The Kenyans run in groups, with a senior member of the group dictating the pace of the run. No one is allowed to pick up the pace on his or her own. Everything is controlled.
This is a difficult concept for most runners to understand. When I was in college, there was a guy on the cross country team who always had to be in front. He would push the pace all the time because he had to always finish each run ahead of everyone else. That’s immature, and shows ignorance of how to train properly. Most runners run much faster than they need to meet the purpose of the workout. I have seen this countless times over my coaching career.
Don’t do runs or harder workouts to practice running faster; do runs and workouts to improve the physiological characteristics that will enable you to run faster in the future. Run only as fast as you need to meet the purpose of the run.
For example, if the purpose of an interval workout is to train VO₂max, run at VO₂max pace, no faster. If your VO₂max pace is 6:40 per mile, run your reps at 6:40 pace, no faster. Running at 6:30 pace or 6:20 pace is not better than running at 6:40 pace when 6:40 pace achieves the purpose of the workout.
As a distance runner, it’s better to run more volume (distance or time) at the correct pace than less volume at faster than the correct pace. Read that sentence again.
Control the pace. Always.