Honestly you dont even need 1x Fair + 1x Unfair deck. You just need two decks that attack at different axis’s. Having Naya Zoo+Merfolk isnt exactly going to give you a ton of options. WHile having Zoo + Blue Moon gives you many. Same for Blue Moon + Storm ect ect. Meta’s generally shift into favoring 2 of the three ( Aggro, Combo, Control ). How much combo control or aggro combo shifts are seen is the hard part to predict.

Agreed, that is really insightful. I might even take it one step farther and say that you might choose a secondary deck that can specifically prey on the decks that shut down your primary deck. Try and map out what decks are good against your number one deck, and figure out what decks are good against THOSE decks. If there’s a recurring deck that beats many or all of your main disadvantaged matchups, that might be the deck to buy into as your secondary.