Much wisdom here (sorry to blow your cover, Bill ).

We could pretend as though the shoe makers were consistent WRT design and construction and especially, sizing. That regardless of the fact all their shoes are all made in any number of ginormous shoe mills flung across the globe, the lasts, material and methods are harmoniously congruent.

You can crush that idea with due prejudice. Variation is so prevalent I've even bought a second pair of a beloved shoe (same model year) and found it to not fit. Which was the outlier--the special snowflake shoes I owned, or the mutant follow-up pair? Impossible to say.

With that said, there are brands that tend to fit me, so I begin with those when hunting a new pair. But, a normally roomy toe box suddenly becomes cramped, or heels suddenly rub, or the instep support suddenly jabs the arches...time to look elsewhere.

Among the embarrassment of riches (Nike alone probably has a thousand shoe models at a given time) it's tempting to throw out any notion of finding the best shoe and instead "settle" for a comfortable shoe at a good price and available at the time one is shopping. Then prepare to go through the whole process in a year.