It depends on your risk appetite. You can test exhaustively, and that's safe but probably slow. I think a lot of shops employ some kind of heuristics to figure

It depends on your risk appetite. You can test exhaustively, and that's safe but probably slow. I think a lot of shops employ some kind of heuristics to figure out what combinations to focus on e.g. "most of my most serious rendering problems happen with language/font combinations that usually take up a lot of space and use non-latin characters at smaller screen sizes" and so might lead someone to test those combinations more than ones that are seen as less risky. Totally made up example, or course, you need to build up these kinds of insights from experience (or buy them from someone - but not me, I'm not a frontend guy). You could potentially test 'diagonal' slices of your test cases - i.e. you might not test every combination of {Edge, Firefox, Chrome} and {English, Chinese, Spanish} - so your test combinations might be something like {{Edge, English}, {Firefox, Chinese}, {Chrome, Spanish}} - then you don't test every combination, but you get a kind of cross-section that tests every one of your test arguments in at least one scenario. Where there are many parameters and dimensions, you can test a few of these 'diagonals' by cutting the test data in different ways to get pretty-good coverage without suffering so much from combinatorial explosion, and pick carefully which dimension combinations you wish to create test scenarios out of.