That sounds very odd. The test normally should take an hour total. If it really took days for an hour at at a time that was a huge chunk of class time. Given that he didn't know all the material on top of that I definitely not go asking for the higher version of the MAP i.e. 6+.
The question I would be asking myself in your shoes was whether this is consistent with his performance elsewhere i.e. is this abnormal processing speed or a sign of something worth looking into.
Full confession: I started opting our kids out of MAP after 1st grade and have been perfectly happy ever since. If he's learning at home, I would trust your own judgement of progress. If very easy to interleave short formative assessments into learning activities that will produce a much more accurate picture of progress than any standardized test can produce.
