I recently purchased several extensions for Catan card-game and noticed that the manual says to put the cards of the extensions into separate stacks at the beginning of the game. Before reading the manual I expected that the extension cards would just be shuffled into the regular stacks, and therefore I was surprised to read about the separate stacks. Unfortunately the manual is not very clear on why those cards need to be in separate stacks. What is the reason for this? And what is the disadvantage of shuffling them into the regular stacks anyway?
I'm referring to this game (notice the table setup next to the box): Kolonisten van Catan Kaartspel
At the end of the page you can see that there are 5 extensions for this game.
My question refers to the manual of the extensions saying that instead of making 5 equal stacks of cards, now there should be made 4 equal stacks of the base game cards, and 2 stacks of the cards of the extensions. So that makes a total of 6 stacks of which 2 contain ONLY extension cards. In my opinion this is a strange rule as it allows a player to search either the base set or the extension sets. I would argue that mixing all cards together and make 5 equal stacks makes a nicer game. Now why is the rule not like this? Is there any disadvantage of making 5 mixed stacks anyway?