I'm chugging through the SOS tree, and I have had to click nodes that get me longer duration of Inn and Greenhouse charms. But I can't for the life of me figure out what a longer duration does for me - other than let me get past them to other nodes. In the field, I can only use inns and greenhouses once every 5 minutes, despite the duration of their enhancement. And other people can also get spell energy and ingredients from these same inns and greenhouses. So... what's the reward?