Nowadays I often only test a few times a week, but when I was mapping out the effect of different foods and meals, I was testing:
On waking
Pre breakfast
2 hrs after
Pre lunch
2 hrs after
Pre dinner
2 hrs after
At bedtime
But I only did that a few times.
I eat roughly the same every day for breakfast and lunch, so once I knew what their effect was, I eased off and only tested waking, before and after evening meal, and bedtime.
Personally, I think taking things seriously is a good thing. So mapping everything out makes sense. For a while. But there really isn't any point in testing eggnbacon more than a few times... Really, it is all about common sense.