Can I pose a question @JHCCoffee With all the other variables in the coffee making process that you cannot control:
The beans being roasted to exactly the same level
The scales being accurate to 0.001% every time
The grinder grinding the beans in exactly the same way
The distribution being exactly the same
The water temperature being exactly the same
The water distribution being exactly the same
The list could go on and on and on and on and on. Do you really think the question that you posed really has an answer? I am not saying this to be critical or take the mick. I believe in good shot preparation but only to a degree. I firmly believe that you reach a point in shot prep, that if you go beyond you are not really seeing any benefit.
When people make the occasional God Shot…….is it an accident or do they set out to achieve that. If it is the latter, can they repeat it. The answer of course is no for the simple fact of The Perfect Storm.
So, good luck in your quest but personally I make 2 sorts of coffee: those I drink and those I sink. I do use a set of principles when preparing coffee because I detest anything which becomes a fanny on. This is probably because I do not have good taste buds.
Many years ago a certain well known US coffee person made a series of videos on the Bezzera Strega. This is a funny machine as although a lever the shot is pump assisted. He made a video or two (this is America, the machine was pushed even harder than the Vario grinder for purely commercial reasons, ability had nothing to do with it). He used a Geisha bean. His pulling of the lever, bearing in mind you could use your tongue to pull a Strega’s lever it is so weak, was quite frankly ridiculous, then when he tasted the coffee he nearly fell over with the effect it had on him. Yes, it was that good and through his presence on their commercial forum, dozens of acolytes bought them to pair with their Vario grinder and firmly believed they had the BEST combination available to man…….meanwhile back at the ranch