Not sure if that is correct any longer:
"For IPS, prior to R80.20, the updates were downloaded to the Management server, and only after you installed policy, the gateways could enforce the updates. Starting from R80.20, the gateways can directly download the updates. For R80.20 gateways and higher with no internet connectivity, you must still install policy to enforce the updates"
Please correct me if am wrong but if gateway HAS internet access then this scheduled install is not needed according to above text from documentation.