Can the shoe experts tell us how they go about fitting someone's foot? It seems the process and choices would be different for RTW vs bespoke, but what do you do? For bespoke, does the fitting start with the shoemakers or the last maker? Once the last is done, how much control is left for the shoemaker?
For RTW, it sounds like one measures HB, width and toe length, then tries to find shoes with lasts appropriate to those values. This requires, I suppose, knowing the properties of a variety of lasts from different manufacturers.
Plus, I assume, people vary in how sensitive they are, how much and where they walk, whether they are comfortable simply removing uncomfortable shoes when at their desks... So two people with hypothetical identical feet might have very different reactions to the same fit?
1) Put foot into shoe.
2) Check the contact patch between the front of the shoe and foot. Improperly fitted shoes make contact to the shoe with the side of the toes. Properly fitted shoes will make contact further down the foot at the ball joints.
3) Check for heal slip.
3) Adjust the shoes if necessary. Increase length to give more space in the toe box. Reduce width to ensure the ball joints make proper contact. (assuming the shoes are too short and wide which is the most common issue).
You'll need to buy shoes from upscale retailers such as Allen Edmonds because most brands don't offer proper width adjustment.