Just my two cents of the past experience. As a release manager of Spark 2.3.2, I felt significantly delay during the release by block issues. Vote was failed several times by one or two "block issue". I think during the RC time, each "block issue" should be carefully evaluated by the related PMCs and release manager. Some issues which are not so critical or only matters to one or two firms should be carefully marked as blocker, to avoid the delay of the release.
Thanks Saisai
