What Affects Tm and Tr In Chromatography?
Think of it like a solvent extract. Each solvent extraction is a plate. 

So at time 1 I do extraction 1  and move top layer to extraction flask 2.  

At time 2 I have two extractions to do. I extract flask 2 and move top layer to flask 3 and then I extract 1 again and move top layer to 2 again. 

At time 3 I have three extractions to do. and so one.



Another analogy. 

Think of the whole thing as binomial trials. Each molecule has a different binomial probability. So the absolute difference in the peak positions between the molecules gets bigger as the number of trials increases.