I am actually at that stage now, where I have thrown away My Camera Manual ... and all other Manuals and *wing it* due to failing memory.
My Personal Memory (in the head) is full up, and I must eject some information to learn new.
You will find this is happening to a lot of older Photographers and it is the Aging process.
When You reach the Age of 50 Years Paul, You will begin to experience things like constantly checking to see if Your Fly is undone and looking with bewilderment if someone says Your Garage Door is open ;]
*salute* from the old bugger Tedz.