How often should I work with this technique?

Initially I suggest you work with the presentation whenever it comes up in this course. It will take you around 30-45mins, maybe a bit longer in the beginning but do not spend longer than 60mins on it. The aim is to spend max. 30mins on it. So make sure to keep the recording to 2 mins max. If you can't seem to keep it within this time frame, just contact me via the comments and I'll take a look.
If you like this technique and if it goes smoothly, feel free to do one round everyday no matter where you are in your current lesson. Make sure to always repeat your presentation topic at least once before changing the topic.

Know that you can chose the topic for this exercise freely according to your needs. Maybe you'd like to talk about a professional topic or a special interest or friend or experience of yours. This is your chance to prepare talks, presentations or conversations about topics that you are interested in.

The idea behind this step

One of the biggest problems German learners have is that they are rarely corrected properly or, worse still, are corrected in an offensive manner. By offensive I do not mean only that one might be made to feel belittled by the corrector, but also that the corrector might rob you of one of the most rewarding experiences in German learning: to find and correct your own mistakes.

But, without any feedback, there would be no learning. The presentation is a wonderfully flexible tool that requires only very little interaction with a native speaker if at all. This way, everyone saves a lot of time and you remain mostly independent in your German learning process. It is important that you repeat the steps above at least once as it is only by sufficient repetition that new information is reinforced and consolidated in your long-term memory.