I haven't observed this issue closely, but couldn't it be attributed to the fact that there's a substantially greater amount of post being made to the
New Code and
New Snippets sections that it is to the
Discussion which causes these posts to 'disappear' much sooner? Therefore, there's little one could do other than alter the behaviour of the entire site as the back-end code that takes care of your posts is pretty much the same for every section.
Unfortunately, my knowledge of this is limited from the point of being a mere user/observer. I haven't yet looked at the underlying
Everything code to be able to render a more conclusive and precise answer :)
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# Under Construction