Boise? August we will be there. Moving plans are forming as I write this.
I think it is common to think that one must run fast in training run fast in races. Reality shows there is no direct correlation. Many runners can do 100 miles per week or more at slow to moderate runs, no fast reps, etc, jump into a couple of races to sharpen up and they are running 2 minutes per mile faster in the races than they have done in training. A great deal of performance is related, I believe, is a combination of high numbers of mitochondria, enzymes, capillaries, blood volume, heart stroke volume, and neural coordination (reduced inhibition).
As it relates to improved race times, I think running a bunch of quick 400m reps improves neural coordination and provides for reduction of inhibitory malaise than anything else. If a runner is doing a lot of aerobic conditioning at modest speeds (lots of distance work), then simply doing a handful of quick reps (say 5 x 300m) on the track with complete recovery is just as good, if not better, for them as running 12-20 x 400m, I posit.
I recall having a discussion with a coach in 1989 who was exclaiming that fast intervals were the reason his xcountry teams' peformances were so good. It was the 4th week of September and his gals had been doing fast 800s, 1200s, and 400s twice per week plus a race on the weekend during the past 3-4 weeks. They had dropped a minute or more on their 5k times already. He planned to keep doing fast reps and then taper for nationals in the last 2-3 weeks. I told him the reason that his gals were improving so much was because they neural coordination was improving a lot since they had done mostly distance work in the summer, and they would not continue improving much longer unless more aerobic conditioning of slower variety was included in the schedule. I told him that if he expected a linear increase in performance throughout the season by doing fast reps he was in for a disappointing finale. He ignored me because I was young and he had enough "experience" to know that to run fast in races you have to run fast in practice sessions.
Anyway, his gals peaked in mid-October, then became slower and slower over the last 4 weeks progressed. His team was rated #1 in October and ended up 5th at Nationals. He couldn't figure out why. Answer: His gals continued doing fast reps week after week and dropped their mileage. It won't work for a 5k runner. Sorry, I don't care what the fancy exercise physiology articles say. I am an exercise physiologist and I think those research conclusions are erroneous. The methods are not close enough to reality in most cases.
It has been my observation and opinion that avoiding distance running at "moderate to somewhat strong" speeds is a serious mistake. The idea that the middle ground between slow distance runs and fast reps is useless is both nonsense and foolish, in my opinion. I have said often over the years that the best runners in history have included fast continous runs in the their training schedules; structured or unstructured it matters not. Why do we not have more marathoners running sub 2:15 in America now? Simple, not enough runs that fill the middle territory of paces, I think.