I guess my point is that it is kind of silly to plot aerodynamic centers to three decimal points, then apply a broad fudge factor and think we are being "scientific".
Of course it is important to calculate a starting point if you don't have a suggested CG from a plan. I have always just used the 25% of chord and that has worked fine for the average airplane. Many folks will complicate this effort with things like "tail volumes" and "static margins", etc. and I suspect that is a waste of time.
When it come to canards, you can sense I have actual hostility toward some theories because they have often proven to be very misleading (you can ask me how I know...) and personally caused me much grief.
I will attach a pix of a canard which I rebuilt three times before I got a reasonable cg location. I was NOT favorably disposed toward the authors of the first two calculation methods. Probably the on-line calculators today are better than what I was using back then - at least I hope so.