I got the impression that not every team did the same type of missions. SG-1 was a front-line team, so they did short term exploratory missions. They had some teams that seemed to specialize in certain areas, ie. archaeology, and those teams might spend longer on a particular planet while they conducted a dig. Another team specialized in diplomacy, as I recall.
SG-9 may have been a team that were tasked with longer term missions, potentially spending several weeks on a planet.