I think you are going into too much theory, and I would suggest you read my very first statement on it.
if doing super fine threads
If you are going a lot deeper, then you will run into all sorts of problems, as shown above.
There are reasons for cutting on the leading face, and that boils down to removing metal without leaving behind the raggedy a**sed threads you usually get when using the straight in technique. What I actually do for very fine threads is to rough it out, without going too deep (hence the shallower angle, which gives greater control of the depth) then use a final straight in approach to clean the back edge up, with maybe one or two tenths infeed. I hope all that reads correctly, I've only just got up.
I find it works for me, but in theory, it shouldn't work. But as with a lot of things, practical doesn't always match theoretical.
That is why I hate it when people start throwing formulae around, it is just too confusing for the laymen who read such posts as ours, it makes them feel so inferior, that they never even try to do something out of the ordinary.
As I stated before, that was what was shown to me, where that old chappie got it from, I have no idea, but somewhere in the past, a machinist must have tried it out and found that it worked for him as well.
But I will say one thing, my tiny threads are always as smooth as silk.
I think where a lot of people go wrong is that they are only looking at standard sizes when threading, say 1/4" diam x 40 TPI. But in fact, you can just as easily have 3ft diam x 40TPI, exactly the same thread profiles, but on a much larger diameter. The critical part is getting that very fine thread to work with it's female counterpart.
Anyone who has visited my shop will see that I can get up to all sorts of weird things, but unfortunately, at this time I cannot show you anything, maybe next year after the patents are completed, but that also includes some strange but very fine threads, all single point cut.
I hope Peter (HS93) doesn't mind, this is a job I am attempting to finish off for him, but here is the sort of thing I am on about. Making a few new blades for a model steam boat variable pitch propellor.
The hub is less than 1" diameter and is full of bevel gears, and the threads have to be a spot on match for the ones already cut in there. Because if they aren't, because of the very tight tolerances on the unit, the whole lot would sieze up. I have made five stubs, just in case I bugger up on the machining to follow.

So as I was saying in a previous post, if you find a method that works for you, use it. If you like what you see, try it, but don't always expect it to be right for you.
Bogs