The 2h post meal idea assumes that this will be your peak - ie at 2h after eating your bg will be the highest. Unfortunately this is not always the case and depends on your body and what you ate.
Some (poorly trained) HCPs don't understand this, and look only at the 2h mark, no matter what your bg does in the meantime (or after). So if you started at 5mmol, went to 20mmol at 1h and dropped to 10mmol at 2h, they would say it's quite good! Because they would only look at 5 -> 10 change, ignoring the 20 in the middle...
Basically, as said above, your bg should be within reasonable (for you) limits at all times. You have to set those limits for yourself, depending on your body and what you can achieve. I usually go for "single digits" and I'm quite happy. Anything above 10 and my body starts pushing glucose out through kidneys, so toilet trips start