I play on Planet Simulator maps and I've been on a maddening run of semi-desert starts, the types where you end up with a ton of unproductive tiles but there's not quite enough desert resources/oasis to make spirit of the desert worthwhile. I've still found Progress to be potent, even with multiple cities with only 5-6 workable tiles. Those cities simply start working specialists earlier than usual.
I used to be very meticulous with my city placement, really aiming for 4 tiles of separation for all cities. I've since come to realize that city distance is not as important as simply having enough workable tiles per city; for Progress that can be as low as 5 tiles. If the land is rich in good tiles I have no problem throwing multiple cities in the minimum 3 tile distance if that makes optimum use of the space. Tile poor lands can go 6-7 tiles between if necessary. I'd rather have longer roads than worse cities.