Lecture mode has to be one of the best and most influential features modern conference calls have. How else can you easily manage a call with fifty, one hundred, a thousand, or more people breathing and coughing and opening bags of potato chips?
With lecture mode on, your participants - no matter how many - can rest at ease to concentrate on your message without worrying if they are contributing to the background noise of the call. You, the host, can rest easy too, as no one can accidentally un-mute themselves, or worse, never mute to begin with.
As a participant, there is one thing you are responsible for: be ready when it's your turn. In lecture mode, you can signal the moderator that you have a question by pressing star 1 on your telephone keypad and you get put into a queue. Occasionally it will take a while to get to you, but you should make sure to be ready. Once you signal, you could be un-muted at any time, so stay on your toes!