For me, currently two: one is normally in serial mode for app testing to simulate device output, but when travelling I just toggle that between serial and normal USB mode so I don’t have to pack as much.
Some of our warehouse workstations also have two, generally for contingency in case one needs to be recharged.
Ideally if Player could tell me the VID/PID of the current device outputting, that would let me know if it was one already connected, or give me the info I need to connect the device currently outputting if it is not already connected.
The current workaround is trying to look in Device Manager and discern which device appears/disappears when connected/disconnected, but for some reason Windows doesn’t list them in order of connection so in the past I just tried connecting all the VID/PID for connected USB devices, which caused me to also connect my wireless keyboards (home and travel one) as barcode scanners, with some funny results.