Homer10,
Not quibbling with the sentiment about "packing out the trash" instead of throwing it out into a lower orbit.
But, I am going to quibble with your description of the orbit the trash goes into. Orbital dynamics are rather counter-intuitive.
Assuming that the piece of junk is pushed exactly backwards from the direction that the ISS is orbiting, and that the ISS is in a circular orbit, the piece of junk will go into a slightly elliptical orbit with only its high point (apogee) as high as the ISS orbit. It will be at its lowest point (perigee) on the other side of the Earth, and it will get there a bit sooner than the ISS, because it will have a shorter orbital period. By the time the two get back to the point in the ISS orbit where the trash was jettisoned, the junk will get there first, and the ISS a bit later, because the slightly lower orbit is slightly faster, it terms of angular degrees per unit time. In addition, because the junk spent time closer to the Earth, it will also have lost energy (faster than the ISS) so it will not get as high at its apogee and would be somewhat below the ISS orbit, even at apogee.
This back-of-the-envelope analysis assumes that the density of the parts is about the same as the ISS, so they react to the drag of the very thin atmosphere about the same. As Pietko posted previously, things that are light mass and large surface area would tend to slow down faster due to drag, but also could respond to solar pressure more and could actually "solar sail" into much different orbits.