Thanks for the link ETOLKIEN! But it's not exactly what I asked
Like S0C9 I can't speak for Cliff, but I am a tireless follower and learned how his method had evolved.
In the early days he worked with schematics and/or by ear, Das metal is a good example of that:
http://forum.fractalaudio.com/threads/das-metal-dizzy.68969/#post-847579
In the present time he needs the schematic and the real amp for make an accurate modelling.
The reason for that is the inconsistency between the schematic and the real amps due to non-ideal behavior of some components.
http://forum.fractalaudio.com/threads/another-v10-preview.62489/page-4#post-775692
In the case at hand of the pots...let's say we have the schematic of an amp, the treble pot is linear: 0 minimum, 5 noon, 10 maximum. Then we take 2 real specimens of that model. With +/- 20% of tolerance we can find a treble pot that behaves "cold" (-2 min, 3 noon, 8 max) and other that acts "hot" (2 min, 7 noon, 12 max).
Then you may find that a extreme setting in the cold amp can't be replicated in the hot amp: you run out of range!!
Plus...we've been talking about one single treble knob, think of all the pots and the inconsistently grows!
A good solution is to implement the "ideal" values because they are central and was the initial idea of the designer.
But...you may find cool to play with Robben Ford or Slash amps...some deviate from the schematic...other are modded post-factory.
I think Cliff aproach is simple: I give you this amp that you want so bad. This is not an schematic, is a real amp. But you can go beyond.
Good news with axe is that you are not constraint to the limits of a schematic, neither a real amp, in fact you can change the tonestack type, choose an active tonestack and widen your range, change tubes, MV location...this amp is not Ford's anymore, is YOURS, this makes you an amp customizer.
I see schematics as shake the dices, the real amp as throw them and the tools inside the axe lets you continue the game: catch the dices, shake and throw them again.