There are 3 main reasons to feed. One is to keep your bees alive. One is to draw comb. One is to increase their stores for winter. At this time of the year, if their brood chamber comb in all drawn, then unless they have no stores at all; I would not feed.
If you need to draw comb now, then feed 1:1 and there is a reason for feeding thinner syrup to draw comb and that is they have to build more comb to store the wet syrup. Feed heavy and keep it going so they are forced to draw comb to put the wet syrup up.
If their comb IN THE BROOD CHAMBER is all drawn then feed 2:1 in the fall after your final flow. In your area it would probably be in October. The reason you feed thicker syrup in the fall is that it takes the bees less time to dry it down and cure it for winter. You don't want to over winter on wet syrup, it needs to be cured some what so it doesn't ferment. Also when I feed in the fall I feed them everything they will take for 2 weeks and then pull the feeders. In the fall hives can take from 15 to 60 pounds of sugar. When they are full they will stop taking. Heavy feeding in the fall like this will also tend to plug the brood chamber and stop the queen from laying in many cases.