Around here, the main flow is 6 weeks long, give or take a week. If you split and remove the queen 2 weeks prior, than the bees will see a decline, about 32 days later, into a 56 day period of main flow. So if you remove a queen, 21 days later her brood completely hatches out, and then a down turn in numbers, (Less than that IF you removed the open brood), and the bees will become field bees about 12 days later. After that point, you will see a decline in bees numbers as well as forage numbers. All effecting honey crop.
The ramifications of pre-flow splitting, can easily go wrong. Requeening part way through the flow, many times can not go correctly. And associated problems can easily erase any foreseen gains by such manipulations.
People act as if there is NO swarm control beyond being at the mercy of other forces beyond what one control by the "splitting". What would you be doing without splitting? What other manipulations can be used? So you use these same procedures until such time as you split half way through the flow.
And this repeated idea, that bees will swarm pre-flow, or post-flow, but NOT during a flow, is about as far from what I see as the truth. And studies clearly show that nectar flow, influences swarming. If your bees are swarming prior to the main flow, during the early spring buildup period, you should practice better swarm prevention and management techniques. That better skill will allow a better crop. Too many beekeepers say right before the flow "OH my gosh, my hives are packed, I think they will swarm, what should I do?" But isn't that what you strive to have going into the main flow? And the standard reply is "Split them". Of course, many times, bees will still swarm anyways later due to the stimulative nature of the on-coming flow. So a beekeeper who relies on splitting as the sole swarm control at the beginning of the flow, lessens his hives ability to make the most honey, and then loses half his bees anyways later on. What a waste.
The idea that swarm control is nothing more than waiting till the bees buildup in numbers, and split, let them buildup and split, accomplishes little IMO. But that is what some do, and it's also the message sent many times. I guess if swarm control with little actual production of honey is desired, this is effective.
Around here, the main flow is pretty much May and June. And I caught MANY swarms during this period of time. You may get an occasional swarm in April, but not many. And July and August are dry and periods of dearth. Swarming lessens during this period. But during the main flow of May and June, one can hardly suggest that bees will not swarm in a flow.
Yes, beekeepers do knockdown splits prior to the flow. And yes, they may actually see a lessening of the amount of swarming. But the goal of this conversation was honey production. And going into the flow with as many bees as possible is what gets you that. If I can get my bees half way through the flow, and they swarm after that, than that still gives me the best chances for a good harvest. And losing a swarm on the downside of the flow, is not a negative. It impacts nectar very little and can actually lessen the amount of nectar the bees eat and use.
And IMO, way too many beekeepers split right before the flow, and lessen their honey crop, for the sole reasoning of swarming. Which is a indication of POOR beekeeping. What?....A beekeeper is expected to go in and do timely splits pre-flow, in attempts to lessen swarming, but can not go in and look for queen cells on a 9 day rotation? If I go in and see swarm cells in a busting at the seams hive, those same techniques will come in handy and I can split, remove the queen, and any number of things. But that same busting at the seam hive, will outproduce a hive that was split prior to the flow.
And I think that the term "splitting" is not the same as some of the manipulations that come under ideas as removing a queen.