When I was an apprentice I had to do the usual 'experience all the different departments' thing and in the Industrial Engineering department they had a frightening example of this that everyone had to learn by heart.
One of the mobile weather radar systems had inspection lamps with 30 foot cables that clipped to the battery for use as general lighting. These are the things that were common back in the 70's/80's in garages and were a bulb in a cage attached to a clip.
Because these were for a military product they had to meet certain specifications which had all been worked out and approved and resulted in lamps costing just over £300 each. Then the bulbs they were using went out of production so they raised a 'minor change request' (MCR) to use a different bulb. Sadly the new bulb needed a new socket so another MCR was raised. The new socket didn't fit in the existing cage, another MCR. The cable needed a larger gland for weatherproofing the new socket, another MCR.....
In total there were at least 8 MCRs raised at a cost of over £1500 per MCR, only 15 lamps were sold at a new cost of over £400 each. Civilian versions in the garage across the road were selling at £5 each