You can square blocks, press the heck out of a quilt...but if you have one little piece out of place, that pressing made look ok...when it gets put on the frame...ah there is when missed issues show up. Usually, I load the quilt and float the top...I check that every block is equal...no extra fullness anywhere. If I find any, it helps me decide how to proceed. Pantos/e2e are nice, but if there is a slight fullness somewhere, or a thick seam...oops! tuck/pucker. It can happen. I do use e2e on customer's everyday quilts...but with computerized quilting...I can take any motif and fit it to a block. There are too many digitized "sets" out there to not be able to use a computer to semi-customize a quilt.
The key is to stay at the machine and watch the job as it goes along