The truth about most grammar lessons is that one lesson is never enough. One lesson may be enough for a language learner to start trying out a new structure, but accuracy only comes with time…and feedback.
Advanced students in particular might have reached a level of fluency where very few situations challenge their ability to communicate, but they could still benefit from a short grammar review. This is especially true about a grammar structure that has less frequency in everyday English. Speakers can sometimes avoid grammar by finding alternative wording, or they plunge ahead and use the grammar hoping that their use is accurate.
If you have students in need of a review of the past perfect and past perfect progressive, please check out my past-perfect_handout. It can easily be used in the context of a group class or private lesson.