Are 2 weeks per tray during refinement the normal process?

2 weeks per aligner is the standard treatment time per aligner. On a few occasions we have actually asked patients to wear each aligner 3 weeks but never less than 2 weeks.  We recommended that aligners are worn 22-23 hours per day and are only removed to eat, brush, and floss. If a patient misses a day or even a few hours we add additional days to the standard 2 week time. We always ask out patients to make sure to let us know if they have any have any questions or concerns. I'm sure your dentist will be very happy to answer or explain the details of treatment related to your case.

It does not matter if trays are for treatment or refinement, trays are 2 weeks each. Any use that is different, more or less, is off label. This does not mean it is bad, it simply is not how the system was designed. 

An open bite is sometimes difficult to correct and during the refinement stage the movements should be more controlled.  Very few of my patients can wear the refinement trays for one week, most if not all are wearing them two weeks at a time.  Discuss your concerns with your dentist and see what he says