I thought you were going to write that.
Now that you can read my mind, you should write that RS2 book!
Thus, it is important to remember that charged electrons can exist for a while inside a solid conductor's interatomic spaces.
Charged electrons are a rotational vibration. In other words, one moment they look like a spatial displacement, the other a temporal one, oscillating back and forth. As a result, they like to hang out on surfaces--the border between the vacuum of space and the solid of time.
When present in a vacuum of space the temporal half allows motion, so they move until they hit something else temporal--like an atom in a conductor. Now they are stuck in a solid of time, and when the oscillation switches back to space, motion starts up again and the progression starts them moving until they run into something spatial. In essence, they follow a chaotic path across a surface, bouncing in and out as they oscillate. Any time you see a charged electron hanging around somewhere, you'll have a boundary condition (like the surface of a conductor).
How much empty space (non time-region) does a block of solid copper have? 15% , 95%? Seems that fast electrons can survive for whole millimeters inside solid matter before they get absorbed. That's a lot on atomic scale!
0.23 nanometers between time regions. But since the time region is 3D time with no structure in space--location only--trying to calculate a percentage results in a divide-by-zero error.
Something else to consider is that a block of copper, as in a wire, is far from a perfect crystal. There are huge gaps between some of the atoms, at least from the atom's point of view. One must also account for thermal separation that also adds space, as STP is far from perfect conditions.
Some electrons could spend years in the copper chasms, and never get out through the barrier of temporal displacements surrounding them.
Every dogma has its day...