Somehow I never realized that GCC has a very regular release schedule until looking it up just now: https://gcc.gnu.org/develop.html
Yeah, GCC’s recent major releases have been remarkably regular, much like Fedora’s spring releases, and their releases seem to fit into the same broader rhythm. Hint? Red Hat.
It has been that way since people from Cygnus (now RedHat->IBM) reorganized the project
IIRC, since GCC got covered by GPL3.
It used to be slower and I've spent way too much time working around C++ bugs in GCC 2.95
(The fact that I remember the problematic version is telling :)
Large projects have been going to regular scheduled releases for a long time. Until the 90's people thought they could waterfall a large release with all your desired features (and for tiny projects this is still a good idea), but as your projects grow (possibly just to small) you reach a point where someone is always working on a feature that isn't ready yet, so a regular release means you still can support your customers with releases. This forces developers who are unsure they will be ready to have some sort of "disabled this unstable feature" toggle, which is about the best you can do.