I think chewy is asking about why certain titles are rarer than others. Some were done in much smaller runs and only once. You can find a fair amount of W. 63rd copies of Cool Struttin' that were actually pressed later in the 1960s after Liberty bought the label, using (I assume) leftovers of the old label and jacket design. Other titles were less in demand at the time and were not repressed - thus you might have 500 copies of a Hank Mobley or 1000 of the Tina Brooks. I think I've seen a non-DG of the Brooks so it probably had a second pressing.
Certainly, if a title is selling poorly it is either cut out or returned to the manufacturer and "destroyed." Supposedly the latter reason is why a lot of major-label psych records are so hard to find. The same might go for certain jazz titles.
Hopefully Chuck weighs in here with some manufacturing tidbits that will fill in all these holes.