We are currently running surveys with a considerable amount of devices. Said mobile devices are given to the surveyors /volunteers so they can fill out the forms while offline. At the end of the day the devices are returned to the office where a WiFi network is available, and all surveys are uploaded/sent.
The process of uploading the surveys to ArcGIS Online is taking between 45 minutes to 1 hour daily. The idea would be to have an additional setting on the Survey123 configuration that allows the forms to be automatically pushed as soon as the mobile device is back online.