Over the past few years I have had the chance to see how the correct balance has a direct effect to increased speed in a runner.
My son has a world class running coach that has competed along side of some of the fastest distance runners on the planet as well as coached a few of them and now coaches a some of the fastest kids in the nation (Regional, state, national, junior Olympic champions)
Running , just like cycling training blocks focus on various targets, you want to run faster? several things will have to happen, running is all about quality of training and volume comes in second. IF you have a running base of roughly 60-80 miles a week you are in a good spot to begin to increase speed. The only difference in running and cycling training is terminology .
IF you have a solid base like mentioned above you need to pick 2 days a week to work hard and can alternate the workouts , Repeats or 200m, 400m, 800m, 1 mile recovery times can vary between repeats 2-6 minutes depending on your heart rate. Doing “Farklets” will also help you progress your running speed.
Your major issue will be the time that you have available to train. I gave up running to get better on the bike and its hard to manage training multiple disciplines , what you end up doing is managing your BASE on one or two and training hard for one…
I wish you the best of luck, stay focused on your goals…