The point of testing is to be consistent with testing pre and post meals that you eat frequently. This gives you some pretty solid data as to what happens when you eat those meals. The phrase, "You cannot manage a condition without measuring," comes to mind. It's all data that you can write down and can help with predictability of levels. And what foods are obviously not suitable. This is of course all unique to the individual, but You can kinda figure out if you want to test less frequently or more so to understand your own patterns.