You definately can run faster on lesser mileage if you train smartly. I think your 400m speed is just fine to reach your goal, but I think you might want to change your goal for right now. Just try to get under 14:30 first, then 14:15-20, 14:10, etc. and just keep seeing how far you can get down. You might reach under 13:40, you might not. Now, think about your training and see where you need to improve, don't just follow a set schedule. We're all individuals and need to work on different things to get faster. Most of the time you should spend at least around 6 weeks of fairly easy running if you've taken off for awhile just to get fit again so you start handling some quality. Since you got injured in the past, I think a good strength training program would help to alleviate these injuries. Specifically focus on the leg muscles, mostly the ones you don't use as much in running. Muscular imbalance can cause a lot of problems. Next, see what you need to work on. Exactly what is it that you need to improve on in order to race faster? I think your speed is just fine for a goal of around sub 14:30, so you probably need to improve somewhere else. Of course, do some speed work to maintain your 400m speed, but I don't think there's a need to be hammering speed work for you, If you can look at other race times (10k, maybe half-marathon?) or just some workouts, you can probably see where you need to improve. You might need more long runs or you might need to do some more tempo work or maybe intervals are what's needed. Study up on what each workout does to your body and think of which ones would work best for you. Break it down, you need to hold 69s in order to break 14:30. Your 400m speed is fine for that, so I'd focus more on speed endurance and simple aerobic capacity. If hammering out long runs at fairly fast paces is easy, then you probably don't need any extra work there and might want to focus on some tempo work. You might also want to have a "test" workout that you use to see your improvements. It could be 12x400 in 69s starting with fairly long rest and decreasing that rest, then possibly doing longer repeats such as 8x600, then 6x800, etc. just to gauge your fitness and racing times. Know the purpose of each workout, be able to tell yourself what each workout is improving on. Be in CONTROL of how hard you're working too. Don't race your workouts, it's better to be more conservative than to try to push yourself beyond your limits in a workout, then be trashed for workouts for the next 10 days or get injured. Know what the workout is supposed to be doing and run it so that you get the desired effect. Don't turn tempo runs into all-out efforts, in fact, no workout should be an all-out effort, save that for your goal races. Consistent, smart, conservative work will ensure that you show continued improvement and won't injure yourself. A final thought is that there will never be a perfect way for you to train and you should always be thinking about ways to improve your training. You mentioned Bannister, he was one who thought about how he could get around his time limitations and get the most effective training to race at his goal pace. He used his medical knowledge and experimented with things. He didn't just follow one set system to reach that sub-4 mile, he experimented until he found a way to get there. Don't be afraid to experiment with your training and always be thinking about ways to improve it. You will never perfect it because there is no perfect way to train, but you can probably get pretty close if you keep experimenting and figure out what works for you. Some people might need those 100+ mile weeks to reach their potential. Some get injured by that or get stale from too much easy mileage and need faster stuff. Hell, doesn't Lagat only train like 70-80 miles a week? I know that he's immensely talented, but high mileage isn't some holy grail that will solve all your problems. Sure, most people will improve on it just because it will get them very fit cardiovascurally, but there's more to it that than that. And sure, some people are probably better running that high mileage, that's good for them, other people have to run a different way. Whatever works best for you.