Bottom line
You can be labeled an "unsatisfactory participant" for missing or coming up short on IDT, missing AT or other ADT, skipping required paperwork, or failing to report when you transfer. What happens next depends on whether you are a mandatory participant or not. If you have a mandatory participation requirement and you pile up at least 9 unexcused absences in a 12-month window (or get flagged unsatisfactory for other reasons), your commander has to pick a path: keep you and give you a chance to make up drills, extend your contract, or start separation.
What it means for you
Showing up matters, and so does showing up ready. A single bad drill (late, unexcused, failed inspection, below standard) can be declared unsatisfactory by your CO/OIC/I-I/OpSponsor, and you lose retirement points for that drill. Stack up unexcused absences and you trigger formal action. The exact count that forces your commander's hand is 9 unexcused absences in the preceding 12 months, and at 9 in a row, the unit must start the process to end your SGLI. The good news: there are recovery paths. Excused Drill Periods (EDPs, the make-up drills) and contract extensions exist so a rough year does not automatically end your career.