Lightning in the distance…

Hello together, I’m interested in how big the distance between speed limit and the speed camera can be maximum? The following scenario: I drive on the highway, in front of a bridge comes a 100 limit without meters, I drive over this bridge then comes a gas station exit and at the petrol station entrance they put a speed camera. My question, can the speed camera be placed about 1200m after the sign at all? There are rules that the speed limit for as long as valid bl until it is lifted or replaced by another I know that, but if, as in the following situation, so many conditions of change and interference affect you, wouldn’t the speed limit sign have to be repeated sometime before you set up the speed camera? PS. I hope we can deal with the topic objectively, because I don’t want the thread to be closed again immediately Thanks!