The every-three-year cycle has changed the development of C++; we are now getting consistent releases somewhere in-between the major and minor releases of old. The 2017 release may be called minor by some, with a huge portion of the planned improvements being pushed back another 3-6 years, but there were several substantial changes in useful areas; it is much more impactful than C++14, for example. This almost feels like a lead-in release to C++20.
The std::variant, std::optional, and std::any additions to the standard
library are huge, and can restructure the way you program (and are available for
older C++ releases through Boost and other libraries).