I was listening to a podcast during my morning 6-miler a few days ago, and the ultra coach was professing that there was a purpose for most every minute of training; anything not targeted for the ultimate goal was a waste and non-productive.
I'm not buying it.
This is the perspective of a 51-year-old man who has been knocking out morning training runs for 25 years. During some periods, I had not missed a daily run in almost five years. I run for the enjoyment of running, and then incorporate racing to put frosting on the cake.
I quit using training logs many years ago. It's good to have a loose idea of what one wants to accomplish, but too much definition can cause burnout and eventual failure.
There have been many endurance athletes who have built stringent plans and stuck to them. But they burn bright and flame out fast. Few who train in that mode last for long. I have known dozens of competitive triathletes and ultra runners who pushed for age group and even overall wins, and when that was no longer possible, they were gone.
I'd suggest we enjoy the sport at an easy pace. There are no junk miles. All miles are good miles. Let them be what they are, and embrace them. Run with a view past the horizon, and run long and slow into the sunset.