considering that an average city in the metro area has multiple shuls and kehillas (BP for example has in excess of 100) the minhag hamokom would be the place you call your primary shul.
We run into a huge problem summertime when multiple kehillas all come together for 10 weeks in one “city” (a colony, as a standalone entity, so I guess you could consider it a city). And boy, do we run into conflicts.