Junk Miles What are they exactly?

I actually posted this question over on Ride Camp as I hear the term "junk miles" now and then while surfing around on the web reading about various conditioning programs. But I had never heard the term "junk miles" defined. What are junk miles? I've always self-defined it as miles on the trail that aren't really doing your horse any good because the horse is ready for something more. If you have heard the term and understand it, explain for me please? As I'm slowly changing how she is conditioned away from long slow miles (we've had a full year of that) and doing shorter more intense rides I want to eliminate miles that are useless to the cause. We are having a longer warm up of about a mile and a half, and a longer cool down of about the same distance, but sandwiching really intense work in between. Why am I making the change? Doing the same thing I've always done has got me what I've always had which is a tired out horse by the end of an LD. She always pushes herself faster on a ride than I would push her on a training run. I want to reverse that if I can. There isn't enough time to turn it around before Top of the Rock, but perhaps by the fall we will have things running to plan.

Okay...so I surfed around for a definition for JUNK MILES. It boils down to this:

Miles added into your training plan with no purpose other than to increase your mileage count. (Sound familiar? Oh....I have to get 30 miles this week).

At some point it makes sense to get more specific in your training goals. I'll admit I still feel like we need to maintain milage, but it is the riding in between that I'm working on. The idea is to subscribe to a quality-over-quantity philosophy. If you aren't continuing to push the margin of what you did last time, how will you ever get better? Notice I said "better", not faster. But in order to get better, you may need to go faster in training replacing some of the walking with trotting, and some of the trotting with cantering. I've been working this new system with Phebes over the past two weeks. I've seen her heart rate which previously was 157+ on the flat at the canter morph all the way down to 126 bpm at one point today as she is learning better how to carry me at that gait and is becoming more relaxed and less adrenaline rushed. I feel like we have so much more to learn, but I do feel that we have fulfilled our base of LSD. We need to maintain that fitness, but get stronger.

~E.G.