That would be unexpected. Not impossible, but improbable. Think about it this way: do you know of any other vaccines with 4-week intervals? If all other vaccines use longer intervals, what are the chances that this particular vaccines needs a shorter interval?
The decisions made in UK and Canada to delay the second dose were not a random choice. They were expected to work based on the body of knowledge we have from other vaccines and what we know about the immune system. It was by no means a certainty, but a strong probability. And it paid off.
For children receiving their first vaccines for the flu (whether inactivated or live), it is recommended they receive two doses 4 weeks apart.
Lots of the early childhood vaccines have minimum spacings of 4 weeks, but are given at 2, 4, and 6 months simply because of standard pediatric followup visit schedules: DTaP, Hib, IPV, PCV13, and Rotavirus. HepB has a first dose at birth and the second at 4 weeks -- 2 months.
HPV is available in a 3-dose series with 4 weeks between the first two doses.
Even Bexsero vaccine has recommended interval of at least 1 months or 2 months, not exactly one month or at most 1 month. It seems to be consistent with longer intervals being ok.
The decisions made in UK and Canada to delay the second dose were not a random choice. They were expected to work based on the body of knowledge we have from other vaccines and what we know about the immune system. It was by no means a certainty, but a strong probability. And it paid off.