We know the professor only has so much material planned for a lecture. If we get it all done before time is up, they have to let us out early. But whenever anyone asks a question or asks to elaborate, that pushes the time we get to leave, back.This is a problem. Most students don't understand the first time around or will forget if they don't talk about the subject matter. And there's a lost life lesson in the importance of speaking up. The reality is doubly a problem for my style since I make the lecture notes available online before each class.
It's tempting to solve this issue by just over-booking each lecture, but it makes you look disorganized. It also creates the risk of having material constantly spilling over to the next lecture until you get backed up at the end of the semester and your homework and exam assignments get out of whack.
So my solution I will be trying out in the future is to create one or two five-minute "widgets" at the end of each lecture. Short extensions on the topic we covered, but small enough that if we don't cover them I don't feel a big loss. When the semester begins, I let them know the rules: if we finish before we get the widgets, then I assume they have mastered the nuances of this lecture and we can further their understanding with applications (which will be now be on the exam). If we don't get to them, they won't be tested over them. Therefore, students are incentivized to ask questions, filling in the time by furthering their understanding of the material in order to avoid a larger exam. Since I have the power to veto questions, I can't imagine I'll be bogged down with filler inquiries in an attempt to game the system. I hope there aren't any unintended consequences I haven't thought of.