Since George Imirie lived in my general area, I have been reading some of his research relative to feeding. From George's March 2001 Pink Pages:
WHEN SHOULD YOU FEED?
There is no special time. You feed bees whenever it is beneficial for the bees and helpful for the beekeeper! Obviously, feeding is necessary when the bees are short of winter stores, so you either feed in cold January or February or let the bees starve to death. Bees absolutely will NOT build comb unless there is a nectar flow in progress, so if you are trying to get foundation drawn into comb, you feed 1:1 sugar syrup as an artificial nectar regardless of whether the time is spring, summer, or fall. One of the most important times to feed is when starting new colonies and trying to build up their population strength, their comb, and their winter stores. Many beekeepers don't bother to feed new colonies in June, July, or August figuring that nature will provide nectar. In Central Maryland, there is rarely any nectar for bees available in July and August; and what about those rainy days when bees can't fly? In almost any part of the U. S., there are some warm months that have very little nectar flow, and new colonies will suffer if not fed during this time.
WHEN DO YOU STOP FEEDING?
It is inherently natural for a honey bee to want to get outside and fly to gather odoriferous natural nectar and pollen rather than being cooped up in a hive eating artificial nectar (sugar syrup) and/or old stored honey. Hence, you can stop feeding when the bees won't take feed anymore. However, this is NOT true in the case of new colonies started in April or May with nothing but foundation. Please note that bees WILL NOT BUILD COMB (draw foundation) in the absence of a nectar flow! Quite often, and particularly in Central Maryland with its nectar flow limited to only April, May, and maybe 10 days of June, if this new colony is not continuously fed sugar syrup (artificial nectar) from the day it was started until September, there will be very little foundation drawn, and maybe not enough to hold 50-60 pounds of winter stores needed to get to next spring!
I know that everyone has their own ideas relative to feeding and feeders. But with this many decades of scientific research in beekeeping, George has some good points.