You're wrong, apple has updated their rMBP this past February. While it is minor, they've not gone 191 days since their last update of any hardware as you ask.
There was some dry spells back in the late 90s early 2000 range as apple tried to get the G5 PPC chipset in a laptop. Their powermacs were set but they couldn't get it in the powerbook lines. I forget the timing but things were not going well for the hardware. One of the major reasons why they finally took the plunge to intel.
Going back further, apple released the Apple II in 1977 and then the Apple II+ in 1979 so the time span between updates was 2 years.