Also time is only a variable in the final product. And at that only a small one, not easily changed or modified.. The ONLY way to tell if variables are in balance is to TASTE the final product. Pour a double into a small cup e.g. 4oz, mix some 1/2&1/2; taste for bitterness, ect... if that's good you’re good to go. Age of beans, grind, water temp, pressure, TIMING are all variables. As a FDA auditor I expected production to be validated for consistency and at times the only way to do that is constant or random QA (quality assurance) tests. See also it's my belief that a large roaster really doesn't have control over storage conditions, post release. Disclaimer: I roast, and have a espresso stand, that lead me to my OPINIONS.