As far as I know itīs also available at Huanggang, Shekou and Fuyong.
Ah, seems you are correct, though Luohu has the longest hours of availability. Seems that the special Shenzhen visa on arrival office hours are
Luohu 09:00-22:30
Fuyong 08:30-17:30
Shekou and Huanggang have morning hours roughly 09:00-12:30/13:00, then close and reopen for afternoon hours 14:30-17:00/17:30.