But to answer your question, I believe 80-100 miles per week is about the max for singles. I have read this is about the range Yuki Kawuachi does. However, he has done up to 220 kilometres in a week in singles. Quote,"One by one I started doing workouts that came to me intuitively like received wisdom from somewhere, something in my head telling me, “You should do this,” and as a result of that my training load went way up. I did two 50 km jogs and totaled about 220 km for the week. I usually do about 140 km a week, so doing that kind of long distance gradually gave me back my self-confidence and physical strength." But another important thing to remember about Yuki Kawuachi is his long jogs quote,"In October I ran 100 km mostly along the Tone River from Shibukawa, Gunma to my house in about 7 1/2 hours. Leading up to Fukuoka I did a lot of 50 km jogs which I hadn’t usually done in the past. ". This is very important, which is something I'm going start experimenting with. It isn't as hard as one would think Yuki Kawuachi sample week looks something like this:
Sunday race or long tempo run
Monday 70+ minutes (Yuki Kawuachi often jogs as easy as a 5 minute kilometer pace on his easy runs. So this could be about 14+ kilometres)
Tuesday same as Monday
Wednesday intervals i.e. 10 x 1k or 20 x 400
Thursday same as Monday
Friday same as Monday
Saturday long jog (I've read these are usually 4-6+ hours on a trail, I've read he has done easy jogging up to 100 kilometres) or he does a race
Another important note, he often does several long runs in a week. Quote, "The second point is that I had increased my long distance jogs. I’ve always done 4 to 6-hour trail runs, but last summer I started doing a lot more of them. Using the Shin-Etsu Trail I ran longer than 45 km two days in a row and jogged more than 40 km three times in a single week. "
Sources:
http://japanrunningnews.blogspot.com/2017/03/the-miracle-in-fukuoka-real-talk-from.html?m=1
http://japanrunningnews.blogspot.com/2017/03/bringing-all-my-experience-into-play-in.html?m=1
http://japanrunningnews.blogspot.com/2017/03/the-lessons-of-past-are-not-outdated.html?m=1