Any model wherein order mattered would imply either a time-ordering or a space-ordering. If things were time-ordered they wouldn't be parallel dimensions, as the notion of a parallel dimension implies (again, purely speaking in terms of wibbly wobbly not-science string theory shit) parallelism along a higher-dimensional axis than combined 3 spatial + 1 time dimensions. A model that goes "out from the center" as you put it, with all events occurring at the same times, needs to imply a spatial separation such that as one moves further out from the center, the information traveling from point X back to the prime universe must go faster and faster and faster than the speed of light to allow for any measure of simultaneity.
This means that for infinite universes, even assuming a near-infinitely small finite separation in space outward from a central point, to go from universe 1 to universe N in the time implied in the show every time they hop, you would need to travel with an infinite velocity. Not just faster than light, actual v approaching infinity meters per second. This also means that Zoom would've never been able to destroy the multiverse no matter how powerful an explosion, because even an explosion of infinite energy traveling at infinite velocity would take infinite time to reach universe N for N -> infinity, so by the time it reached really far distances, billions and billions of years would've passed and the explosion would mean fuck all to anything past a certain point.
Infinite universe theory is fun but also dumb as all hell. The only way it works is thinking of it as infinitely many universes at the exact same point in space and time in terms of lower dimensional. Separation needs to occur in embedding to higher dimensions, but if Barry and co. can travel through like 8th dimensional space it sorta makes the concept of punching someone in the face a bit mundane.