PCB Redundancy

Ok, just last Friday our PCB was sent off to fabrication. This was the result of many hours of work - particularly to get the multitudes of miniaturised components to all fit in together (see the layout pic).
In a meeting with our supervisor we were given the advice - I'd have two, or maybe even three boards made up. The explanation was board 1 will be the original board. Board 2 will be the replacement when we destroy the original (remember this is an aircraft flying 100" up). Board 3 wouldn't get made up and we could use it as a reference to see where all the tracks go. Since we had only ordered one board initially - another is now on order with one week latency :)