In my experience one of the most common causes of recurrent plugged ducts
is an ill fitting (usually too small)
nursing bra that is worn all of the time.    Many, many women are still
being told that they need to wear a bra all the time to prevent sagging
and to help with engorgement.  Sometimes different bras that a mother has
will press on different spots and cause plugged ducts.  Depending on how
many bras a woman has she might be getting around to the offending one
every few days.

Sarah

Sarah Friend Barnett   LLLL, IBCLC
Bronx (New York City), NY  -  [log in to unmask]
" You are not obliged to finish the task,
 neither are you free to neglect it."       R. Tarfon