>>So to be clear, what I'm asking is if I only connect one device to one of these fingers, will the other fingers (not connected to anything) cause some voltage drop?
Cause voltage drop? No. Not if they don;t draw any current.
Experience voltage drop? Yes. Because the first cord is shared & has current flowing through it, hence the others tap off a point that already has a voltage drop. But if there is nothing connected to the others, then it does not matter much. Seems a pretty academic question?