Agree! Applying a robbing screen in the midst of a felony-in-progress always (for me at least) gives the appearance of making things much worse, at least temporarily. Bees on the inside of the screen pack the protected area, bees caught outside - would-be robbers and foragers, alike- mill frantically or hopelessly around the screening. And I think the upheaval may even ellicit some kind of panicky, mass-hysteria which draws many indoor bees out to rubberneck.
But if you need to use one, just do it. But I would rarely close it off completely, except for a few minutes, to do something urgent. I generally use two anti-robbing devices at the same time: I have a form of ventilated entrance reducer (not the typical wooden one in this case) that allows me to make the normal entrance just a bee, or two, wide. Plus I also use a separate, screened device that stands about an inch or so proud of the front surface of the hive and which covers the whole entrance area and has another entrance limiting device. I usually set the outer one to the smallest opening possible, the thickness of my little finger, while allowing the inner excluder to be a bit more generous. This arrangement gives guard bees several battle stations from which to manage the invaders.
I have at times felt that things were getting a little too out of hand inside the robbing screen and temporarily removed it for a few minutes to evacuate the mob behind it. If I let a few robbers out with their booty, I'm OK with that if the result is a better organized battlefield for the defenders.
Upper entrances are a bit more complicated because they occur on the flat plane of the hive front. But you can make anti-robbing boxes for them, too, and simply screw them accross the joint of the shim and box below or above. I have some made by Betterbee that were intended for nucs which work just fine, although they are small (approx. 6" sq.) so they can get packed full pretty quickly.
If the first day it seems chaotic, usually by the end of it bees are starting to sort themsleves out. Robbers may find too little opportunity to score and move on; foragers caught outside will eventually get a clue and bees inside wanting to go out will figure out the exit point and the guard bees will have sorted the hash of any robbers caught in the act. So, at dusk, when the invading hordes have presumably gone home to a nice supper and their beds, take the robbing screen off, allow the "home team" bees to all go in, too. Late tonight, or before dawn the next morning, reinstall the screen. That way tomorrow anybody who leaves has to figure out the new secret passage. Some profoundly focused "gotta-get-to-work" types won't make a note of it and will be confused again on their first inbound run, but that will diminish. You may have to do this again for a day or so.
This assumes that hive is still in the right place. Moving it complicates this quite a bit, and so, absent other things I would replace it where it started this morning. Easier all around, I think.
I'm pretty new at beekeeping, but I've decided from my experiences so far that whenever there is disruption, or major inequality among my closely-placed hives, and there isn't so much flow going on that turning to felony-acquisition is more trouble than it's worth, robber-screens go on as preventive measure.
So, I've added adequate anti-robbing devices for each planned hive or nuc to the ever-lengthening list of "stuff ya gotta have". And to think that last year I was taken aback that you needed a base, boxes, frames, and both an inner and outer cover for each one. Little did I know!
Good luck with your crime wave.
enj.
