so once I'm in the clear of those jobsworth types, which is sometimes once on board the aircraft
Sorry Phileas, don't agree with you there. I too have prepared myself prior to reaching security (not like the two women the other day who nattered incessantly until it was their turn and only then began their 5 minute preparation ritual, keeping all behind waiting). All my needed items are in one compartment of my carry-on bag. As soon as I'm through security I find that there are always areas immediately after where one can reconfigure oneself. When I board, all items I will need during flight are on my person or in my hands. As soon as I reach my seat the bag and coat (which I have taken off whilst waiting for the other punters to sort themselves out) goes into the overhead and I'm straight into my seat. If all passengers boarded fully prepared the procedure would be much more efficient.