How do you hold your direct reports accountable for training/developing their reports?

I identify training/certifications goals that I want them to achieve.

In the past, I would ask for certain hours of training each week, but that sometimes was ineffective, they can go to the training and generate reports that the training has been done but can stay on their phone and read Twitter... so I switched to asking them to pass a certification, they can train as many hours as they'd like or not train at all if they already have the knowledge.  I encourage them to book time in their work calendar dedicated for training,

Top down goals process tailored to each role