You have hit the nail on the head. The more stops there are, the more time the train needs to slow down and accelerate, and the longer the trip will take. We have to minimize the number of stops if we want to minimize travel time.
When Bombardier and its partners prepared the proposal for a high-speed train from Quebec City, the train was to stop at L’Ancienne-Lorette to pick up commuter passengers. Then it stopped at Trois-Rivières and, finally, it stopped outside Montreal. It didn’t stop more frequently in order to minimize travel time.