In the type of game Doyle is talking about, he can invest 20% of his stack because of his "streak" he can steal the pot when his opponent misses the flop. Not superstition IMO but playing based on how the opponents perceive you.
You know damn well there have been times when you were getting dealt garbage, but the others at the table had no problem believing you had the goods, so you played the terrible hands to take advantage of that. You know when to stop playing the streak, when they start playing back at you and start defending against you. It's not that complicated. You have to exploit any advantage you get, and that is one of them. When it appears to the others that nothing can go wrong for you, they back off.