Is there any reason not to promote short term breastfeeding?  
Well, it depends.  There are lots of reasons not to portray breastfeeding for three days as a first choice, and I'm sure that isn't what the question was about.  But if a mother is thinking of giving it three days, why stop her?   I would not pretend that this would be easy or unproblematic; she's likely to be really bothered by engorgement.  But her baby will have gotten three more days of breastmilk than if we told her not to bother at all, and the three first days are the most important. (If you're only going to get breastmilk for one day, the first day is most important - or for one week, it's the first week - etc.)  Unless her decision is due to scheduled start of chemotherapy for cancer, she may want to keep on for a whole week or a month or whatever, and if we'd told her it wasn't worth the effort for three days, none of it would have happened.
I would have serious qualms about advising someone who just gave birth as if I were assuming she would stop breastfeeding after three days, but I can envision situations in which it could be appropriate - and in that case, who better to guide her than someone who knows about the normal course of breastfeeding, with lactogenesis II starting right at the time the mother is planning to stop breastfeeding?  A woman like that needs good care.
Of course we can't go around saying 'breastfeeding for three days is the same as breastfeeding until your child weans on its own at age 7'.  But all breastmilk is good and some is better than none.  
I guess I always have an assumption of continuation as long as mother is available, when I meet women starting to breastfeed.  But I know that women sometimes stop abruptly and I'm notoriously bad at predicting which women will do just that.  I advise everyone as open-endedly as I can.

Still, the question brings sad associations to mind - imagine having a baby and being well-informed enough to want to breastfeed, but feeling you were unable to commit for more than three days at the outset.  

Rachel Myr
Kristiansand, Norway

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