Maindeck lets me learn subdecks in random order

I would expect that when i study the Maindeck that i get new cards from my subdecks in order of the subdecks, and that it lets me review upcoming cards from all my subdecks. Like i go to the Maindeck and it just feeds me new cards according to my daily limit from the subdecks in the order that these subdecks are in, and that it lets me review "up for review" cards of all the previously studied cards of all the subdecks.
But what is instead happening is that if i study my maindeck, i get random cards from all throghout all the subdecks in random order. Wich is not very helpful at all...