If you’ve been using our 80/20 plans, consider “leveling up” to the next Level to make that next breakthrough. If you have been on the Level 1, go to the Level 2. You can always switchs level for free with 80/20 plans.
If you are doing you own custom plan, I’d focus on 800M and mile repeats, something like 4-6 x 800M on 5-6 minutes easy, or 3-8 x 1 mile on 1-3 minutes rest. A killer HM workout is 12×1 mile at race pace on 2 minutes rest, but you have to build up to that based on the previous mile repeat work.
Sure, you can work on general and specific training at the same time, but that is rarely as effective as true periodization: first focus on building your base threshold and speed, then switch to the specific demands of your event.
You can pound the miles while you build speed, but pound too much and you can’t recover fast enough to build new speed the next time.
Yes, getting leaner will automatically make you faster, but it’s not my expertise.