There is one very big drawback with the continuous approach as you've described it: the students get no direct positive feedback from attending a lecture. That means that the effort of turning up to a lecture goes unrewarded for a long time, which may seriously hurt the attendance and motivation.
I like to spend at least a little time considering for each lecture how the students will feel afterward. I remember best the lectures where I really felt like I had learned something. A kind of feeling of exhaustion and exhilaration at the same time. The sensation that you now know more cool stuff. I feel if I can achieve that feeling in my students I can keep them coming back.
Moreover, people have a natural attention span of about 20 minutes. It's best to plan your material in chunks of 20 minutes, and plan for a small distraction in between those chunks (some interactivity, or a light video).
Finally, it really helps students to give a layout of the lecture beforehand, so they can plan their attention levels. If they have no idea what's coming, how long you're going to be talking about X, and why it's important to know before you move on to Y, they'll lose focus. It's very hard to maintain your focus when you don't know what you're supposed to be focusing on.
If you don't give some thought to where you want to end up after each 20 minute chunk in your lectures, there no way to achieve this, and most likely you will just drone on for an hour, eat in to the break, and end up losing student's attention, and then students.
Of course, the flip-side of a rigorously planned lecture series, as others have pointed out, is that you lose the flexibility to adjust to how well the students are absorbing the material. Here's how I would start:
- Make a list of learning goals: what should the students absolutely learn, what would be nice for them to learn.
- Plan your course requirements (exam, report, practicals, everything that adds to the grade) to reflect these learning goals and their relative priorities.
- Create a preliminary series of topics on the basis of the learning goals. Make sure to focus on the information required to achieve the requirements. Chunk each lecture into 4 20-minute sub-topics.
- Make sure to check at every opportunity whether the students are following along, or falling behind. Ask plenty of questions during the lectures (for instance, between these 20 minute chunks), and try to talk to students one-on-one whenever possible.
- If you find out that people are falling behind, re-adjust between lectures. Adjust the planning, scratch some of the minor learning goals. But change the plan you had, rather than not having a plan to begin with.