Slowing way down on easy runs, and running a lot more easy miles, was what did it. If I worried about running faster - on average - in training, I'd probably be a lot slower in races.

It is difficult to understand this concept, many people repeat it. If running slower is the real answer than why don't good runners run at 12mm pace in training. If they want to race faster why not after a few months of 12mm training pace, do they not then gear it down to a 13mm pace?

Its not about running slower and slower and slower. Its about running at the right pace for your current body and cardiovascular system to provide the most benefit overall. The fitter you get the faster that will still be, but it is slower than 99.9% of runners want to run when they first start. The objective of these runs is to build blood volume and to increase muscle strength, endurance, and aerobic fitness. It allows you to build a strong mileage base with minimal stress on joints and connective tissue. It helps your body learn to burn fat as fuel at higher efforts leaving glycogen burning for race efforts. And it leaves you fresh enough that when you DO go to race or do speedwork you have more to give and can take advantage of that. 2 years ago I did my long runs at a 9:30 pace and I raced 10K's at a 9:15 pace. Since then I slowed down my long runs to about 10:30 and last year did 10K's at a 8:45 pace. Since then my 10K pace has dropped to ~ 7:50 and my long runs are aroun 10mm

That's not what you asked. There are obviously diminishing returns of more and more mileage and there is a physical as well as practical limit that is different for everyone. Most elite marathoners running 140 miles per week would not do better on 170 miles per week, if anything they would break down and do much worse. But most people running 30 mpw would do significantly better on 60 mpw.

you mean "you are a little faster than me"..... way to confuse your grammar fool. "I" is a nominative pronoun.