A lot of the breakage you might encounter with rolling vs iteration distros is due to upstream desktops, such as KDE and GNOME.
Much of the stability and reliability from, say, Ubuntu LTS, is that they “freeze” the versions of GNOME and KDE, and if everything “just works”, it’s going to remain that way for the life of your distro.
On the flip side, if there’s a bug in an application, you may never receive the fix, not even backported, if by chance it’s arbitrarily frozen at whatever version was available during the version-freeze phase of Ubuntu’s release cycle…
Take Smb4K for example (part of KDE’s ecosystem). If you’re on Ubuntu 20.04 LTS, you are still using a buggier version of the program (3.0.4), while Manjaro users are gifted with a version that has fixed these bugs (3.1.1). In order to use version 3.1.1 with Ubuntu, you need to “leap-frog” from Ubuntu 20.04 (LTS) to Ubuntu 21.10 (non-LTS), or find a PPA and take your chances with it. So much for “long-term support”. 
Recently KDE, at least from my perspective, seems to be a bumpy ride with a rolling distro, such as Manjaro or Arch, due to the regressions and new bugs that are introduced in its current development. Honestly, I think less frequent updates in regards to KDE would benefit most users. (Sudden “surprise bugs” in the file manager or desktop-integration are not fun.)