In a good week I used to manage 275km, this included 2 club runs, a Sunday solo run and 90km of commuting.
Last week I managed nearly 70km offroad which is a new record for me (not counting riding holidays). I have 85km pencilled in for this week. Would have been 170km but I have plans at the weekend. I’d be very happy to hit 800km (500 miles) total for this month though.
It needs to be part of a training plan. I can’t just go out and go hard every time, and it needs to fit in with life. For example, I was supposed to ride 45km this morning, but I’m not feeling 100% after some broken sleep and I have to meet some friends this evening so I’m resting instead.
It is easier if you commute and ride road. 800km off road a month would very likely break me, or be unsustainable.