

Switches will flood a network when they don’t know the location of a MAC address but this should only happen for the very first packet which is more likely to be DHCP or some boring background thing like that. As soon as the correct devices get the packet and replies then each switch along the way will update its MAC address table and they’ll know exactly which port to use until it expires (which depends on the switch, I don’t have a ballpark idea).
The flooding a network thing really isn’t an issue, they’ll only flood for the first packet just to find the way and then it stops. Fire up Wireshark on a different machine and transfer a file between two other machines, you won’t see anything. I don’t know too much about WiFi but it probably does the same, it’s just a bridge to the same network.
Wired is probably better because machines can estimate your location from the SSID and they can leak the password giving access to the network.