Some historical perspective:
Old Openwrt infra had a really cumbersome release generation system, which contributed to slowing the release frequency, a release every 18 months or so in 2010-2015. And there were several months between RC versions.
That was one major reason for LEDE fork split-off, and the LEDE buildbot / release mechanism was redesigned to be more lightweight. LEDE 17.01 was released in Feb 2017, and there was a 17.06 on the roadmap with dates. The published goal was 2 releases per year, I think.
LEDE was pretty much on track with that, but then the Openwrt/LEDE merger talks started again and the merger got accepted in May 2017, which prevented new LEDE branded major releases. But the merger only finally happened in early 2018, leaving things in limbo for quite a long time.
Early 2018 saw some new features, like more targets with 4.14 and flow offloading. Then the planned 18.0X got delayed at the last minute due to the DNS outage (of the old Openwrt domain infra) and then it took a while to get the buildbot into green status again, as some minor changes broke some targets during the outage.
Regarding the previous discussion viewpoints, I pretty much agree with the main tune of the discussion. Frequent releases are good, but they need to also have good quality. I feel that the release target dates are both for a deadline for including new features, and for branching the release branch as soon as all looks good in buildbot (as it makes no sense to branch when compilation is broken). Then after the branching 2-3 RCs get compiled and the branch has a few weeks time to mature before the final release.
All developer activity tends to stay on master, so getting the final release off rather quickly after branching is a key priority. Otherwise the RCs just float around, although no real development happens any more in the branch.
Having also followed the Firefox development for years (with 6 week release frequency), the rapid release train keeps things moving and brings new features to the end users quickly. The endless beta of buildbot snapshots is ok for enthusiasts. but not for the general user populace.
For Openwrt the goal of 2-3 major releases per year is more realistic, taking the complexity (devices, kernel, feed packages) into account.
Hopefully after 18.06 we are again on the path for more frequent major releases.