"Scan this many devices simultaneously" setting: what does it mean?

In WiFi Guard settings, there is a scanning option named "Scan this many devices simultaneously".
What does it mean and do? And what number of devices should I set it to?

Simultaneous scanning means the app will scan several devices at the same point in time. A higher number allows you to finish scanning faster, but it may require more resources, e.g. memory.

Leaving it somewhere in the middle is a good start. If you have a very fast computer with lots of memory, you can set it higher and see if everything still performs well. If you have an older/slower computer, you can decrease the number of devices.