The problem with "industry standards" (still holding back till I know the real source) like these is that the uninformed may make costly mistakes in bidding their work because they will accept this at face value and not look at their own records and be realistic about what THEY are capable of doing, not what others say that the should be able to do.
Also, it would be easy to say that a 10,000 square foot job would take 10 hours at 1000 square feet per hour. However, few of us are in the physical condition to be able to clean for 10 hours straight and be as productive as when we started.
While I find even 1000 square feet per hour for hot water extraction a stretch, if I accept it, its more fair to call it 1000 square feet the FIRST hour, with a declining production rate until the first break.