Debian unstable follows more or less that "CI/CD" approach you're describing, but it is called unstable for a reason: sometimes, a significant change is necessary, which may lead to significant breakage as well, but most of the time, you get small breaks here and there, which are usually easy to fix (and hopefully report, so that break can be handled by the package upgrade process directly).

I wonder how's Arch in that regard. You speak about breakage less common, but there has to be some significant breakage from time to time: for instance, for a shift as important as moving from traditional sys-v init scripts to systemd, it must be expected that a lot of OS configuration related packages would break, unless every package maintainer is made aware that this change would happen, and that he/she has to prepare its package (if necessary) to that shift, AND that the shift only happens when everyone's ready. But Debian (and I suspect Arch as well) do not follow such a rigid scheme, and so there has to be breakages and fixes to follow.