My status: on H1, visa expiring in September 2007. Rajiv's team applied for my H1 extension and I had I797 approvals till 2010. I had an H4 extension approval done for my wife as well. There is no employer change from first 3 years on H1 to second approval.
This link below shows the average amount of time it takes to receive a decision in a particular type of case after the case file is received by the AAO. Processing times are directly related to the volume of cases received.
http://www.immigration.com/processing-times-status-checks/aao-processin…