I have not read this thread completely yet, but wanted to respond to this:
I do cut foundation in half and insert half a sheet in the center of frames, but it is the correct direction.
Below is an example of a newly mated spring queen, not interested in rearing drones so the rite cell foundation in the center is laid up with brood, large cell foundationless areas on each side filled with nectar.
When started making mini frames years ago for mating nucs, I did accidentally install some foundation in sideways. I found they avoid using it for rearing brood if they possibly can. It took me a bit to finally realize what I had done and why they were avoiding the frames. You'll find in wild comb building, there is a fair amount of oddly angles cells. They are usually very large cells and I rarely see brood in any of them. I there is, it is usually drone brood.
And while appreciating the theories-experiments which do sometimes shed light on better or unique management, (I certainly have been known for reinventing the wheel at times) I try to stick with the realities of the nature of bees, climate/ weather extremes and other occasional challenges one faces from year to year.
I had the unique opportunity to do a LOT of experimenting over the years, as I had few losses, too many hives and had the freedom to 'fail'. I rarely did however and learned a tremendous amount about bees behavior and management is a very short period of time.
But when it comes to cell direction, I'll say, the more uniform frames you give them to work with, the more uniform the end result. Lots of young healthy bees trumps a lot of the small issues that humans tend to fuss over.