Once an LTS or interim distro is released, after few weeks, Ubuntu moves to another repo, whose name is not yet known. But, the repo “devel” stays on. Considering some of us always moves onto the “next development” release, why not change the name of the repo to devel? That way, we’d be having a rolling installation, of course, with all the problems it might bring in. After all, that’d what we are doing here – using the development distro.
The thing is, even the LTS distro can be pointed to the devel repos, which is simply there and within reach.