Hainan:
Looking back at LFs, July-Sep were the best months at 87.8%; 88.3% and 87.3% from the CAA stats. based on all flights being the A333 with 292 seats. The airline has quoted 92% I gather for the summer.
Oct-Dec dipped to 72.0%; 66.8% and 73.9% also based on the A333, but we know A332s were used part of the time, presumably due to lower booked loads, so the actual LFs would be somewhat higher.
It would therefore not be too surprising if frequency increased to daily for a temporary period, although the use of the smaller B788 with 79 less seats may enable frequency to be maintained with the benefit of daily flights possibly attracting extra passengers.