Running version 3.0.1 Professional. When scheduling reports, the entire ReportSchedule object is serialized and stored in the JOB_DATA column of Quartz's job details table. The ReportSchedule object has a ReportUser, which has a list of ReportGroup objects, which have a list of Report objects. This means that every report that a user has access to gets stored in the JOB_DATA column to schedule one report.
If a user has access to sufficiently many reports, the serialized ReportSchedule becomes unnecessarily large and can exceed the set size of the JOB_DATA column.