Yes, it also depends very much on what you eat.
The main reason some of us test directly before we eat and then two hours after we eat is to determine what effect certain foods have on our BG levels. So for example, you may test before breakfast and then eat porridge. Don't drink a sweet orange juice, just eat the porridge and don't put sugar in. You want to see how the porridge affects you. Then, test 2 hours later. That way you will learn how porridge affects you. Also, you have to do it a few times becaus doing it just once doesn't mean much at all.
When I started, I knew something like a slice of roast beef wouldn't push my BG levels up because there are no carbs in it. But, even something as simple of a beef sandwich had a huge effect on my BG level. The culpprit was the white bread. It transpires that it is as bad as putting sugar in your tea (or porridge).
Eventually you end up with sore fingers but a lot of knowledge on what you can eat and what you must avoid.