I used to regularly ride 400+ weeks, with a few over 500 and I think one week was nearly 700. I don't tide that much anymore because I am racing, but I still somewhat regularly get in weeks near or over 300 miles. Last week was 360 miles and this week so far is just under 300.

Edit: I should add that it took me a few days to recover from last week's effort, especially the road race on the weekend, but mid-week (this week) I was able to get a PR on a local hill climb.