I happened to be in Northampton the other day and popped into the Church's factory shop. If you've not been, I can heartily recommend it. I had only intended to have a nose-around, but channelling my inner Imelda Marcos, I ended up buying a pair of Grafton brogues in calf and with a Dainite sole. These are open throated wingtip brogues. Discount about 40%..

I normally wear a G fitting - but have found that what amounts to a G is a term of art. The Graftons were in an F fitting on a 173 last - this is a longer form than most of my other Church's shoe examples, but having an open throat and the wingtip design giving a little extra width, they are snug - but not tight - but oddly in my view, snug all the way around the quarter. Theres quite a lot of length room due to the last design.
I suggested to the very helpful and evidently knowledgeable lady serving that I thought I ought to have a G fitting because that's what I normally have. We fell into conversation on the topic of fit and she expressed the view that all shoes should fit snugly when new, since they will only expand with use and that looser fitting shoes are undesirable as a matter of principle. She added that some G fit lasts are only really noticeably wider at the heel (some feet need it apparently).
On reflection, I realise that all my G-sized shoes & boots are perhaps a little on the generous side, and I wear insoles in a few of them to reduce friction. On the other hand, my uppers never get distorted because they are never under any strain.
Maybe I have fallen into the habit of wearing overly-large shoes? (Im blaming my childhood with 3 older brothers whose school shoes were passed down to me until I was 11 by which time I had bigger feet than they did..)
How should shoes fit when new?