You should try to keep the number of SSIDs as low as possible
Service Set Identifier or “SSID” is the name of the wireless network. SSID allows users or devices to connect to the desired network when multiple independent networks operate in the same physical area.
One of the most commonly cited best practices among Wi-Fi professionals is to limit the number of SSIDs you have configured on your WLAN in order to reduce the amount of overhead on the network and to maintain high performance.
For every SSID there are data packets the AP needs to send to support it. These are referred to as management and control plackets. When you add multiple SSIDs then that management and control planes start to eat up the air time that could be for data packets. So more SSIDs the less time there is for you to get data packets.
Using the WiFiScanner, a user can check how many SSIDs each network has.