It really depends on the map. From my experience, I've seen that a map with minimal revisiting of old locations that an average speed play through would take an hour on, the map should be finished in 8 hours if built poorly. A mediocre build of the same status should take about 12 hours while a beautiful and elegant map of the same should take about a day. For me however, I just don't have the patience and end up only making a five minute map with poor style, which takes probably 2-4 hours.
