It all really depends on the device hardware and what interference they see.

My iPhone to Subaru OEM radio: Drops out if my I swipe my hand over the phone in my pocket while sitting in the seat.

My iPhone to Pioneer aftermarket radio: I can be walking well into the house before it finally drops off.

Dualshock 4 controller with Bluetooth adapter plugged into the computer: Struggles to stay connected.(Due to motherboard interference.)

Dualshock 4 controller with Bluetooth adapter plugged into an USB hub a few feet away: I can play games I can't even see through floors.