That is true... That trick only makes a poorly working drive though, I think..
Most of my heads are not open, but very high (15k) resistance on one side of the coil or the other, so I disconnect that side of the coil from the board and replace with 12ohm resistor to the center tap.
It can then read, but not that well... I think you are only getting half the signal strength, so many errors and some fast loaders don't work well at all...