Not completely clear on the "interlooking" thing. I don't see how one could tell too much from just looking at the bottoms and up into the frame from below "spreading the frames like a book". Sure you could see queen cells in the making but I wouldn't think you could see brood very easily? Do you just lay the box on its side and check each one?
How frequently do you check your hives during the flow? I thought that was a time you could pretty much leave them alone, but perhaps that is one of the times that demands the greatest attention i.e., ensuring bees not backing up the brood nest, supplying adequate super area, making sure no swarm prep is underway and if it is doing something about it?
By interlooking, I can see what I need to. I don't have to look at the brood in every hive. I'm looking for two things, primarily. Queen cells, of course. Also amount of brood. One of my yard sheet entries is how many frames of brood at reversal. This tells me how they wintered, and how the queen is laying. This is on the Dandelion/Fruit bloom...not the main flow which for me is a month later.
I look further at some colonies. These I do a complete inspection on.
I take apart colonies with cells started...even if just 1 cup with an egg. I evaluate the brood pattern, look for disease, count brood frames. Look for pollen/honey stores.
I also look at any colonies not making the grade, looking for disease and queen problems.
I look at the rest of the colonies later in the season for disease check and queen evaluation. All colonies have their brood looked at once a season. I don't check colonies during the flow that are strong productive colonies. Rather, I look at the colonies that appear to be behind. Once the main flow has begun, there really isn't any reason to check the broodnest.
When I reverse, I lay the hive on it's back...lay it right down. Take the bottom board off. Look up into the hive to see how far down the cluster is. I crack apart the top box...no lifting involved here...the hive is on its back...no working against gravity, with an all bent and twisted back. I look up intop the hive, count brood, look for cells, etc. When I'm finished with the top box, it is placed on the bottom board. The middle box...I use 3...is checked next, and placed on the first. The last box is checked and placed on top. Supers are replaced and additional supers are added as needed.