If we want to eat keto (which we do, don’t we, boys and girls) we would never eat the suggested 50g carbs in one go. But I can see a value in a modified version of this test - using, say, 10g or 20g carb. You could use it to decide if any particular carb was giving you a problem compared to others.
Or proteins. Don’t forget they can cause both glucose and insulin responses.