Difference between 顺顺当当 and 顺顺溜溜?
bkrs： 顺顺溜溜 smoothly and obediently 顺利不受阻挠。
红楼梦．第三十六回：「先时在外头关，那个月不打饥荒，何曾顺顺溜溜的得过一遭儿。」no frequency rank, 1 usage example at https://dict.naver.com/linedict/zhendict/#/cnen/example?query=%E9%A1%BA%E9%A1%BA%E6%BA%9C%E6%BA%9C

bkrs: 顺顺当当#35152 by a happy chance; win in a canter; smoothly; easily，smooth and easy (of tasks/etc.)顺顺当当过日子 many more example phrases at bkrs, 10 usage examples at https://dict.naver.com/linedict/zhendict/#/cnen/example?query=%E9%A1%BA%E9%A1%BA%E5%BD%93%E5%BD%93 users can draw their own conclusions which is the more common more modern term