The three failure modes
Spreadsheet drift (multiple versions), unrecorded off-line training (safety toolbox talks not captured), and site-manager memory as the only record.
What good looks like
Every training event logged at moment of completion, per-guard transcript retrievable in seconds, aggregate reports filterable by site, guard, contract or period.
Client-facing reporting
Quarterly PDF or dashboard link. Guard names, licences, CPD minutes, incident-training coverage. Answers the client's audit question before they ask.