There doesn't seem to be a problem with having parts for production bikes. The problem is not having any extra parts on hand or in dealerships to replace failed parts on sold bikes.
Note that any smart assembly line ensures that all parts for the end product are available and inspected prior to starting assembly. Bad as it sounds, humans are the weak spot in the assembly process as it is impossible to determine if they'll show up on schedule.
Retired USAF, IYAAYAS!
2008 V-Star 1100 Custom Bobber project
2011 Crimson XR with Forged Highway Bars / Hard Bags / Passenger Backrest, Ness parts including Smooth Layback Plate Frame/Mount / Rad 3 Mirror / deep cut grips / drivers floorboards /shifter peg / brake peg / passenger pegs. Witchdoctor black rack, Lloydz filter / timing wheel / VFC III, 7Jurock windshield, Drag Specialties seat.