I never fully follow the book and I don't play an aggressive style. I don't like to double down against face cards and aces. I usually only split when I'm against dealer's 5 or 6.

With that said, I don't change my play much whether I'm playing seriously or playing for fun. I might play a more aggressive style when it's just for fun and I'm betting much less than I usually do. But that's just me. A lot of people split 8s against 10. Double down on soft 18s. That's not me.