Every job is different. There is nothing to standardise.
Every job is different in the menu and identical in the shape: a count, a set of exceptions, a load list, a timeline and a quote. That shape is the same for a wedding and a company lunch, which is why the second one should not cost you an evening of arithmetic. What is custom is the food, and nobody is proposing to standardise that.
We have done this for years without any of it.
You have, and the memory that makes that possible is genuinely the skill. The problem is that it does not scale and does not transfer: the day you run two events at once, or the day the person holding it is ill, everything that was carried in one head has to exist somewhere else. Writing it down is not a criticism of the memory, it is insurance on it.