Reps are not ignoring your CRM because they are undisciplined. They are ignoring it because it has been wrong too many times. The contact who changed jobs six months ago. The account assigned to two reps. The phone number that rings to a fax machine.
Every time a rep follows CRM data and wastes a call, they learn to distrust it. Within a quarter, your reps are building shadow spreadsheets because the official system cannot be trusted for the work that pays their commission.
The fix is not training. It is not gamification. It is not another "CRM hygiene week." The fix is making the data accurate: dedupe, enrich, validate, and decay-score on a schedule. When the CRM is right, reps use it. When it is wrong, no amount of management pressure changes behavior.