I realized I half answered this question about faster 4 mile timed runs yesterday. When I stated you need to run more 4 miles timed runs to get better at running 4 mile timed runs - that is true. BUT I left out the other runs of the week you should also do:

Hill runs, sprints, should be a training day.
Goal pace 400m 800m and  mile repeats should be a training day
Beach running (if available) should be a training day.
- Add a 4 mile timed run to a mobility day and work on your 4 mile running strategies (pace, fuel, hydration, etc)

We were already doing these workouts and he asked if he should just do more. I said no - just add a 4 mile timed run each week and watch it come down each week. And it works.  For more ideas on training see:

https://www.stewsmithfitness.com