If a method of teaching works, that method should be used for teaching the teachers in your PD sessions. For example, if you're teaching cooperative learning but you're lecturing about it, that's undermining the message.
The best PD classes had us teachers create lesson plans that we could use within two weeks of completing that class.
Then, using a rubric created for the class, we would try out the lesson we'd created in our PD session less than two weeks ago and receive feedback from a trained administrator or a peer. If you wait to implement, you'll never implement.
After receiving feedback, teachers worked on another lesson. This approach of lesson design, lesson performance, and feedback is powerful. Not surprisingly, important features found in a recent study included integrating new knowledge, learning together with colleagues, and being actively engaged in meaningful discussions (van den Bergh, Ros, and Beijaard, 2015).
"Drive-by training" is rarely helpful. Without local acceptance, accountability, and follow up, teachers leave the PD class with continuing education units and not much else.
PD should fit in with the long-term vision for a school or district. Some teachers groan about their district's "technology du jour" approach.