A checkbox on each tier of a nurture campaign (this could also apply to blast campaigns, but seems less necessary) that would limit a student to receiving only the first item in the tier that they qualify for. Then if there are changes that qualify them for another item in the tier, the system would instead hold them until the following tier where they would receive the next intentional piece for their new status.
This would resolve many issues where we want to include multiple stage-based emails in a tier but cannot effectively do so because EMP would send a student a second item in the tier if they change stages before qualifying for the next tier.