The deck(s) is(are) shuffled after every hand.
The advice is based on my own analysis and basic strategy tables for one, two, and four+ decks. If you do, the change will not take effect until the next hand. If doubling or splitting is mathematically the correct play, but you don't have enough chips, the game will give the best advice for what you can afford to do. I recommend that before you play for real money both online in person that you practice on the game until you very rarely are warned you a making an inferior play. If you make an inferior play, the game will warn you first.
This is our first blackjack game and trainer and I'm proud to finally add our version 2 with enhanced graphics and the ability to learn how to count cards to my website.