> The main purpose of scan is to update/confirm the
available WiFi SSID list around the user’s device. There are
two types of scan: active scan and passive scan [3]. The
active scan is triggered periodically: the mobile device first
broadcasts the probe requests, and surrounding APs after
hearing the probe requests will reply probe response packets,
containing information such as the supporting physical rate.
The mobile device will add the SSID of the AP into the
candidate list, if it finds that the AP is compatible. In the
passive scan, the list of available SSIDs can be updated by
beacon packets broadcasted by APs periodically, e.g., every
100ms [4].
In any case, a good protocol would have random wait times that are still (in expectation) of order the rate at which bits are communicated, not some human timescale.
Relatedly: When I turn off a network by pulling the plug on a router, it takes many seconds for this to be reflected in the list of available networks on my Macbook. I don't think there's a good reason for it to be like this.
