Great observations! Actually the US06 test is normally done as a hot start test both A and B. This avoids the problem you cite. Further, if you read our EPEP test procedure
http://www.pulstarplug.com/pdf/epep.pdf. you will see that before the US06 is run we perform 3 dyno pulls and 3 acceleration tests (40-80 MPH). Then we run the US06. As you can imagine the engine warm! Your point about returning to the A test has been considered and tested. We have not seen any complelling evidence this makes a difference. Of course, doing an ABA test without scientific equipment would make a big difference!