Even after developing accountability and self-management skills
, you need to track their progress once every two weeks. On a particular day, ask them about the ongoing task and when they will be able to deliver it.
Being a leader, you should avoid distractions in your communication that day. Just speak directly about the work. This may sound weird, but believe me, it will bring a sense of accountability in your employees, and they will get to know that you are there to ask for the work.