You then need to walk from the gate to passport control and the luggage/customs area – this process can take anything up to 60 minutes, depending on gate location, immigration queues and number of border posts open. Obviously if you have checked luggage to pick-up this will slow you down a few more minutes.
Is a one hour layover at Schipol enough?
KLM Royal Dutch Airlines, Schiphol's largest carrier, recommends a minimum connection time of 40 minutes for flights within Europe and 50 minutes for an international flight.