On thing to consider is microbial growth in jet fuel, namely if planes that fly once a week or less. Any time my king air flies after sitting for a week or two I notice that It often develops several ounces of red algae along with water contamination.

Keep in mind that a pt6 would probably burn a gallon of water without an issue, but when you set takeoff power it's nice to have the piece of mind that you got all the junk out.