I have made 4 reasonable decks for the 4 warbands out so far.
How feasible will it be to keep these decks premade for casual games to save time? How will it affect replayability?
Would it be better to rebuild a deck after every 2 or 3 games, or even every single game?
What I did for my play sessions where I most of the time host the full game and all minis/cards is create 4 ready to play decks. (I couldn't resist picking up the according sleeves and dice either )
2 of them want objectives (Skeletons and Uruks), 2 of them are just out for different goals (Sigmar and Khorne)
When people visit my place I give them full disclosure about the main goals of all the factions and a quick overview of the objectives.
Then (because they are usually not playing as much as I am) I give them firstpick and let them hand me another deck.
This procedure has the obvious problem, that it comes down to a slight rock/paper/scissors effect (with the sigmar deck being extremely defensive, etc.).
In addition there are no surprises in the decks for either player - but honestly for a casual level of play it seems to be sufficiently fun so far. (we have about 1 after work gaming session every 2 weeks)