Overall a Fokker 50 burns 600 kgs/hour at almost any level. To minimise fuel burn and flight time you flew for maximum ground speed, whatever the level. Yes we had marvellous fuel burn and cruise tables. They were basically useless. Given still winds, you climbed until your climb rate fell to 500 fpm or so and levelled off. That is your cruising level. If you ever looked like exceeding VNO, you climbed another 2,000'. This could result in a throttled back cruise at 6,000' to avoid a headwind or handling on the props at FL250 to get into a low jetstream.