Some people just do not understand Hulks power. It isn't a increase anger that make Hulk as strong as he is. It isn't the fact that, if he gets madder, madder, and madder, the more power he taps into. That's all he has to do is get pissed, once that happens...his powers continues to increase. It doesn't have to be at a certain level of anger...him being just pissed continually increases his stats and the only way to stop this is by calming him down.
Modern day Hulk doesn't even need this anymore...he has complaete control of his power, so he can increase his power just by thinking of it...willing it to happen.
So again...him getting pissed is enough to make his strength grow to enormous heights. He doesn't need to keep getting mad at different levels for his strength to keep jumping...him being pissed is enough to make his strength grow exponentially.