Transport for London have long found that there is a point when people stop looking at timetables, and simply turn up. A 15 minute frequency is credited with the initial success of the London Overground for example. For their bus planning, TfL state that once you get to 12 minute frequencies - or better - people stop looking at timetables and just turn up and go.
https://content.tfl.gov.uk/bus-service-planning-guidelines.pdf (see page 4)
With that in mind, the individual gaps between services there to me look very much like the kind when someone will just turn up at not worry about when the next bus will be, because they know there will be one soon. Certainly I wouldn't be looking at a timetable in that scenario.
It's very different when you're looking at one, two or three buses an our (or even less). Very different when you need to plan. But with high frequencies you simply don't need to plan. I lived in Greater London for many years and very rarely looked at timetables. Hey, it's hard to even find a proper timetable in London. I know we're talking Greater Manchester here, but I seriously doubt it's any different at all. I genuinely believe most people will look at those intervals and not care one bit that they're not equal, as long as they get to a bus stop and don't have to wait too long.