Understudy, I have mixed feelings on that. 5 out of 7 colonies I lost last fall I had treated.
The 5 I had to survive had no treatment what so ever. "all" queens were 2 yrs or older. I have noticed in 7 yrs I have been keeping bees, if a colony looses the queen during a good flow they keep right on gathering nector.
As of right now I'm looking at 100+ lbs of honey per colony. Even the two swarms I got this year. I was lucky to have drawn comb frames to give them. The first swarm filled a deep up in 10 days.