That is NOT what I said. I said 90 degrees was not doable and to sail one tack upwind then the other, to be able to tell the angle (course) between tacks, i.e., in the same wind, stb vs port tack close hauled. That's all.
Forget awa, vmg, instruments and everything else. The ONLY question IS: if I sail upwind on one tack A, and then do it on the other tack B, what is course A and what is course B? The difference is what YOUR BOAT can do.
Disconnect this logic completely from the techniques of tacking, which is a separate subject entirely.
Ask: What is the difference that YOUR BOAT can do.
I guess I don't understand at all what you are saying, then. And, I don't think you are understanding what is meant by 90 degrees, in this context. What is meant is 45 degrees off the AWA on starboard tack + 45 degrees off the port tack = a 90 degree turn. Again, this is about right - not exact for most boats and conditions, but a pretty good rough targeting angle when picking landmarks. Surely you are not saying this isn't the case. I am assuming you are saying something else, but I am not understanding.
You said that 90 degrees was "monstrously incorrect" and "nuts" and you thought it was "way too tiny". That suggests, to me, that you are not understanding what that 90 degrees was meant to refer to. Are you suggesting that the Merit 22 would not sail efficiently upwind at
about 45 degrees off of AWA? I don't know exactly what that angle is, but I promise, it is
about 45 degrees.
That 90 degrees being "way too tiny" is only true when talking about a multihull or a heavy full keel boat like mine. Even so, I use that 90 degree mark because it is easy to calculate and identify. I just know that I will fall a bit below that mark.
You really lose me with "forget AWA, VMG, etc." This is never about what your boat
can do. It is purely about what produces the best VMG which is all about sailing the optimal angle relative to the AWA. My boat
can sail almost 30 degrees off the AWA, but my SOW drops to near zero and VMG tanks. My boat's best VMG tends to be at about 50 degrees off AWA. Russ' Merit 22 will probably be closer to 40 in most conditions.
I am not sure what you are saying about the importance of knowing the difference between the angles of pointing as high as the boat will point on each tack. That angle is irrelevant. (I guess it is good to know, but it tells you very little about how to sail quickly or efficiently.) What is important is the angle relative to the AWA at which you make the best VMG.
We must be talking apples and oranges because what you are saying seems to make no sense and I don't think you don't know what you are talking about.