I would say it depends on flows in your area. I was SE Iowa now NE Missouri and generally August is light to non existent unless you are having good ground moisture. Even so there would probably be a lull in August unless you have something like late panted soybeans that will be flowering in August, like I am just getting into now. The bees here are nuts into honey. Not all soybeans generate nectar I read.
If it was me, I would pull excess stored honey and plan to feed syrup if the flow stops to stimulate brood building. Just stored honey may not keep them building. Incoming flow generates that best. You also should have a good flow in the fall depending on your location and soil moisture. One catch with that is if you have fed them a lot already. If you did, they may mostly have sugar syrup stored and you wouldn't be pulling honey.
I wouldn't look at honey stored as much as size of brood nest and colony. If you feel one is weaker and want to equalize the hive strengths, better plan would be to move a frame of capped brood from a strong to a weak hive as needed. You can shake nurse bees off or leave them on, but don't move a queen over to another hive.
If your three good hives are double deep brood nests, you may be set well to go into fall and generate a good winter supply of honey for them.
If it was me, I would pull excess stored honey and plan to feed syrup if the flow stops to stimulate brood building. Just stored honey may not keep them building. Incoming flow generates that best. You also should have a good flow in the fall depending on your location and soil moisture. One catch with that is if you have fed them a lot already. If you did, they may mostly have sugar syrup stored and you wouldn't be pulling honey.
I wouldn't look at honey stored as much as size of brood nest and colony. If you feel one is weaker and want to equalize the hive strengths, better plan would be to move a frame of capped brood from a strong to a weak hive as needed. You can shake nurse bees off or leave them on, but don't move a queen over to another hive.
If your three good hives are double deep brood nests, you may be set well to go into fall and generate a good winter supply of honey for them.