My experience with using stretch is the torque readings vary greatly. The last time I used torque angle specs provided by Tom Molnar. The stretch numbers were very close. The torque numbers were recorded using a Snap-on electronic wrench. The numbers were much closer together. Sneaking up on stretch creates a lot of friction skewing torque readings. As stated if you don't have a good method to measure each bolt at the start and finish and keep exact records the entire process is useless.
Doug