The Immigration Department of HKSAR has announced the revised enrolment criteria for automated clearance service to Singapore passport holders.
Under the existing arrangement, eligible Singapore passport holders aged 11 or above who have visited Hong Kong for no fewer than three times within 12 months prior to enrolment can enrol for e-channel service in Hong Kong. With effect from 13 December 2018, eligible Singapore passport holders who have visited Hong Kong for no fewer than two times within 24 months prior to enrolment can enrol for e-Channel service. Other enrolment criteria under the new arrangement will remain unchanged.
You may wish to refer details on website: https://www.info.gov.hk/gia/general/201812/12/P2018121200318.htm.