I see you have decided that "the hive" is the root of all the causes and thus "the hive" must be fixed.
Not so.
A complex, multifaceted problem you have.
Fixing your "wrong" hives and making them "right" will not entirely fix your bee survivability (if fix at all).
For some reason, you never mentioned once your bee management as a whole.
Well, have fun.
I too enjoy building the bee hardware. The bees will come along.
Greg, this is one of the reasons I dislike the internet, and text based forums in particular. You have completely taken away almost the opposite of what I am intending, what I have done, and what I am doing. Not to mention, misunderstood my reason for asking about the horizontals and tbh etc. Let me try to be very clear, and perhaps we can be on the same sheet of music.
1. 5 years in and I have not gotten to what I consider a level of success. Therefore, what I am doing is wrong, either because what I was taught is wrong, or how I am interpreting it is wrong.
2. I am an excellent woodworker, and have made all my equipment save one piece because we had to have the gabled copper top roof to look pretty in the garden. There is nothing wrong with my equipment, as it meets the patent design of LL Langstroth, at least to the current 3/4" thickness of the modern recommendations.
3. Having come to conclusion #1 and being bee-less at the moment, it seemed like a great time to tear down all the equipment, perhaps harvest the wax, maybe do some scorching and repainting. Fix any weather damage, and other wear since the stuff will be out of direct need for a while.
4. After breaking down everything, and finding my back sore beyond effectiveness, I packed it all up in the shed, and went to the chiropractor and instead of going back to it and starting the cleaning and painting process, I started surfing the internet. I came across a small but loud bunch of folks that were shouting from the roof tops the wonders of horizontal hives for easier on your back working of hives, and their Profit was Dr Leo Sharashkin. So I went to his site and read everything he had to say, I bought his books, and read through them with an open mind, and watched everyone's videos that mentioned him and came to the conclusion that this might just be the way to go!! I sent him a few emails with a couple validation questions, and imagine that, not a reply, not even an automated reply. Nothing. So now, that I have read and absorbed all this stuff, and for the most part bought into its philosophies as truth, I started to think that rather than spend the time cleaning up and painting and whatever, all my existing equipment, I can make whatever new equipment necessary, if I wanted to follow his philosophies, and techniques.
5. So given a few days, and weeks, I start scouring for other people doing things this way, videos and such. But mostly all I see are builds, and initial installations and so on. I do see other people using long langstroths, which, from what I am reading seem to contradict some of the original things I am seeing. So now I start asking questions. This is what has lead me back here.
So with what I have read in his books, well someone else's books, translated to English, and one in the public domain, that was translated from French... Maybe I bought into the snake oil, but maybe what he is saying works in some way. Maybe you can do beekeeping with 2 inspections a year. Maybe you can overwinter bees better on deeper frames, maybe, some of what he is saying isn't all smoke and mirrors, to sell speaking engagements and books. But it doesn't taste right. When looking at the differences between the different formats and sizes I see where in colder areas where the flow is like this or that, this size does better, and in warmer... etc.. But then it doens't all necessarily jive. Because all I have to compare it to is what I did with double deep broodboxes without additional insulation and following the regular normal vertical "common practices". Maybe bees can be raised without chemicals, and prophylactic medications, and stuff. Maybe they do know something instinctively that lets them be bees and make their own winter nest and do this and that... So I am digging, and looking for some confirmation that somehow supports any aspect of what I just spent good folding money to buy books in hopes that they are not simply fairy tales.
However, using OA and rolls, and feeding, and all that stuff, I can still slay bees, and repurchase them every year. Hell, I was looking forward to swapping those bottom two brood boxes....

If I can kill them doing what is "common practice" I don't suppose they could end up any deader if I try "natural" or "treatment free".
I am all for a good conspiracy theory. So it is not hard to believe that thin walled, inset handled boxes that can be palatalized and sent to California in support of the evil big almond might not be right. So it is not a big leap to think, maybe thicker better insulated boxes might be better, and cause less stress and resource loss for both heating and cooling. And it might be wishful thinking that if I had a hive that was laid out horizontally and I didn't have to hump supers up and down, it might make it more enjoyable. I can also buy that the chemical industry wants us to buy their chemicals, and blame all the bee deaths on pests and diseases, so we continue buying their products, especially since we just made the pharmaceutical prophylaxis much harder.
So help me to understand what the next 5 years should look like. If horizontal is not just a gimmick, then my back would love nothing more than to create a hive that allows that. If natural beekeeping or treatment free beekeeping is just "crunchy granola bull cookies" then bring on better living through chemistry! I have read stuff that basically says everything I have read up to this point is wrong. I just too the Penn State Ag Extension's course (they were letting people do for free) and I passed it with 100%, and nothing they said, isn't something I haven't already been following, because it sounds exactly like what I have been doing..... until I started reading Dr Leo's stuff.
Do I still sound like I am reaching for the silver bullet of "If only I use the other shape things will be better?" Because that is definitely not how I am trying to come across. Do you hear the pain and confused frustration in my words?
Sorry for being so long and wordy.