Some teachers are unclear on the difference between 'planning' and 'preparation'. This difference is subtle, but important; the two aspects have different benefits, and different drawbacks.
To plan something simply means to decide or arrange it in advance. In TM4T 'planning' means deciding what we are going to do before we do it and writing it down.
To prepare something means to make it ready for use. In TM4T 'preparation' means physically collecting, selecting or creating the resources.
So: if - for example - you are considering next week's Citizenship lesson, then writing down the objective, the topic, and ideas for a starter and a student activity are planning. It is quick, it is mostly easy, it is valuable.
Producing a worksheet, generating a PowerPoint presentation, making a quiz for assessment, and working out exactly what you are going to say - these are examples of preparation. It is often time-consuming and sometimes problematic.
Note: it is preparation, not planning, even if you do it waaay in advance, even if you do it at the same time as your planning.