I am pretty sure that I read that this is done on purpose, that the flag
can touch the note head and that the distance of the elements of a 16th,
32nd, etc. flag are derived from the distance of staff lines. But after
quite some searching I could not find the article I am talking about.
And I think there are rules how long the stem should be depending on the
position in the staff - not on the shape of the flag. In other words: If
the collision should be avoided, the flag glyph would be different, not
the stem length. But I may be wrong.
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