原句的travel to指的是nearest town.后面的on Saturdays for shopping or on Sundays for church就与前面的独立了.你可以拆成两个句子:They travel to the nearest town on Saturdays 和They travel for shopping or for church.如果用visit换就得换整个travel to,也通.
至于内容...老外一周去一次超市是很平常的(travel是广义的,不一定是去旅游景区)