When a developer uses run time Markers (which is what happens when he/she uses the CreateMarker Block and he/she has a Map control on his/her Screen) the placement of the marker appears instantly. once the CreateMarker 'creates a marker. How this is implemented is up to the developer; usually by using a for each number Block. There are literally dozens of ways to do this
This simple example posts two markers from a fixed List. It pans to them and ensures the Button that creates them only runs once. The National Park Tutorial posts several dozen markers and could literally post 100's. 
