Sorry but that is not an acurate statement. Most linear actuators will go untill you tell them to stop. The ones he linked to will do just that. hook it up without limits and it will rip the door off. The timer would be needed if he can only supply a 12v pulse. I did car audio for 17yr and did a ton of motorization. plan this out from start to finish or it will be a disaster.
Quality over quanity, that's how I make my mistakes....