One of my conditions for signing up for the Rockin' Rockwoods 53km—or any race for that matter, even just the 10km race at the J—is to be able to steadily walk up the mileage week-to-week. Mostly this isn't a physical thing (although obviously it is that), it's a mental thing, a confidence thing. When I was training for Western States in 2012, my routine was: from a starting position (50 miles/week), run two weeks at that level, then bump it up 10 miles/week, two weeks at that level, etc., until I got up to 102 miles in a week. Just like that, I went from fairly lousy shape (discovered what an IT band is while recovering from Ozark Trail 2011) to getting a silver buckle.
I didn't really log that mileage at the time in a permanent place, just kept track of it and then wrote the series of weekly mileage levels on my wristband so that I'd remember the work I'd done to get there. It's not like I would have forgotten, but it strengthened the message-to-self when the going got tough. After that I stopped logging altogether—it was stifling. I just ran and let the distance flow by like a river, not bothering to catch it or name it.
In 2016 I started logging mileage on my mobile phone (manual entries in Runner's Log—no tech on the run, wear running shoes and throw wooden shoes). In 2016 I still had some residual monster shape left. In 2017 I had some second-order residual shape (30 miles/week wasn't too tough, but no 40s). 2018... vapors. Some 20s, no 30s.
Logging is mostly for purpose of shame now: look at the horrible thing you're doing, self.
That's where I had to pick it up in the last week of June: 20 miles. Then 25. Then 30. Then this week 30 again. Even better, this morning was a 15-mile run, which I've not done since January. (The pace is still very much no bueno.) So the legs are still there, for the most part, but the habit is not. That's the next frontier.