The purpose of planning

Finding the perfect planning template to me is like finding the Holy Grail. It just doesn't seem to exist. I have looked at so many different examples of people's planning and have tried lots of different ways but I am still not sure I am happy about what I am using. So I want to delve into the why part of planning. Why do it? Well there is the obvious things -
 1) So you know what you are going to teach that day/session and
 2) Evidence to justify what you have been doing with your class.

I am a big fan of the overview for planning. I think this is because I would consider myself a flexible teacher who prefers not to be too structured. An overview allows for all the ideas and does not fix them to a time or place. My writing overview from last year was so enjoyable to write. It included all the types of writing my class would do over the year. For me it was my philosophy of teaching writing all on 2 pages. So is having "Writing" written on my weekly plan enough??

Reading is also an interesting area to document. Does there have to be a focus in a guided reading session? Is it necessary to provide "time fillers" for after a book? I am really interested in self-directed learning and am going to try using Daily 5 in my classroom, first as rotations then into more student directed learning in Term 2. I really want the reading time I have with my students to be worthwhile but I wonder if it is totally necessary to prepare questions for comprehension before hand or note down decoding strategies for focus for those on the colour wheel?

NZMaths has wonderful numeracy planners that outline the key questions for each stage with links to resources. Is highlighting and scribbling notes enough or does there need to be a more structured day by day plan for each group?

I guess I am grappling with the need to be flexible with my teaching but also requirements that force me to be structured. My school uses Split Screens for planning.  This is from Guy Claxton and is about integrating dispositions for learning. I wasn't sure of the purpose at first because it wasn't explained very clearly to me. Then I had a go myself and I got it and it suited my style of teaching perfectly (that is going to need a whole other post). I'm still not sure if Split Screens are ok just by themselves?  Then we just got introduced to Concept based planning for our term long inquiry. This also sits very well with me.

What I am wondering now is with the move towards team teaching how teams plan together. What planning is necessary and how long should planning take? How many plans does one actually need and which is the most effective?