One problem I know we have been having recently is lack of testing for edge cases of Lubuntu when doing a new release. Sure, we could just smoke test the ISOs, and that solves major problems, but we have a problem with people not testing the edge cases until they need to run them in production, which is absolutely a problem. I know that as we approach the LTS, this is going to become especially important so we don't have another fiasco like 17.10.
There should be a page, probably on the wiki here, that documents cases Lubuntu as a team should get testing for prior to releasing a new version of Lubuntu. It should probably be similar to what Debian does for their QA processes (you can find an example here), and it should be a prerequisite to marking the final images as ready. These processes could probably be started as early as the final beta freeze, and as a team we should watch for updates that could require retesting of any of these between the final beta freeze and release (by watching $RELEASE-changes).
It's a bit late to do this for 17.10.1 but I certainly think it's accomplishable for the final 18.04 release. I'd like to leave this up to QA to implement, but I definitely think it's a step in the right direction.