Qualitative Benefit of Longer Sits

I have recently tried meditating for 15 min at a time, at least once per day. I'm wondering, however, if long sits have a *qualitative* benefit. In other words, I'm wondering **whether longer sits have a benefit other than *more* of those of shorter sits, perhaps uniquely different benefit/s?** (Here, longer sits would mean about 1h-1h30).