That only rarely happened under Jobs.
The iMac knocked everyone's socks off, or at least got them talking. In 1998.
Three years later, in 2001, the iPod did the same.
Then there was a period of steady product improvement and necessary technical changes until the iPhone launched in 2007. Six years after the iPod.
Then thee years after that, the iPad launched.
It's now been less than three years since the launch of the iPad, and people are saying the next revolution is overdue? It's never been like that.
Apple's big product launches have had a space of three to six years between them. The rest of the time has been a period of incremental improvement and behind-the-scenes product development... just like now.
If in three years time, Apple is still touting the iPhone, iPad, iMac and Macbook as their main products, then it will be time to start talking about stagnation.