It's definitely market dependant. To HKG it looks like the "good" fares go away after 12/8 and return on 12/24. The best fare currently loaded ex-SFO valid in early December is QLXAPHK @ $884RT + tax
SEASONS
1SEP-8DEC OR 24DEC-31MAR THE FOLLOWING YEAR. SAME DATES APPLY EACH YEAR. SEASON IS BASED ON DATE OF ORIGIN AND IS DETERMINED BY DATE OF DEPARTURE OF OUTBOUND TRANSPACIFIC SECTOR.
Keep in mind that this is what is loaded into Sabre and there may be better (S,L,T) fares available on united.com.