I wish I recalled my records, I think the highest I ever heard was 426 hours billed in a month (not by me). The most I ever got was 125 in a week. I found I was happiest and most productive around 60 billable a week. A few weeks of 90 plus is like being dead.
I'm afraid I am still looking for the right balance, I'm thinking of jumping back on the high speed treadmill and have started to look for a new job