Are 2 weeks per tray during refinement the normal process?

The main goal of the treatment was to fix an open bite. After the last tray of 20 trays, the bite was still an issue. I asked for refinements so at least the canines would touch. I found out that I needed 13 trays at 2 weeks per tray. Although 13 trays are understandable, I thought during the refinement stage, each tray were only supposed to be 1 week each.