For local trains you need your loading and unloading time to be as fast as possible anyway. People have places to be, waiting around on your trains and platforms is not on the list of things they want to do. It is even worse when they are waiting around not moving at stations they don't want to get off at. 60 seconds is the absolute longest any train door should be open for, and 45 is reasonable. (it can be pushed to 30 or even 15, but that starts to be impossible for the disabled and so not worth it)