Delivering 75% to 80% of reports in 48 hours is the goal, and we measure against that goal (otherwise, why have it?).
Over the past two years I have spent a lot of time looking at how appraisers manage their time. For a residential appraiser, managing appointments and overall assignment workflow is a large part of the business side of appraisal. Some are very good at that and some are not.
Some do live/work in areas where it is tough to do. But for those working in urban and suburban settings, it is simply a matter of efficiency and time management. I have a guy out in the Portland area right now. This time last year his turn time was at three to four weeks, and three weeks is still the norm in the area. But we worked together on time management - scheduling appointments, actually scheduling time to write reports, etc etc. Today he is making a killing because he is providing turn times that are 1/3 of his competition. He bills at a premium rate due to his service, and AMCs and lenders are very willing to pay, because they are getting something in return for that. All it took was using some very basic time management techniques. As you noted, bundling inspections is a huge part of that.