My theory is that the transistors are either full on or full off. You get the same instantaneous current when the transistor is on. Speed is determined by how fast the controller pulses that current. As you go faster, the duration of the off times gets smaller as the wheel spins faster, and you use more current. Still, at low speed, you draw the same current.
So I don't think it matters either, unless you help the bike start by adding some decent leg power. That will be easier on the gears in a geared hub motor and easier on the motor in a mid drive. I don't think it makes a difference in directdrive.