As the mad one that measured all the boats and sails at the 95 Globals with the help of Mark and Paul - around a quarter of competitors had at least one or more sails fail measurement.
74 competitors, 4 rigs per competitor, 296 rigs, or 592 sails - that was a lot of check measuring!
Some manufacturers are very close to the maximums allowed in varying class rules, so much so that you can quite easily believe in a bit of stretch over time will render them out of class. Something like a marblehead can take up to 4 hours just to measure the sails/rigs if the sails are made very close to the maximums, again you're measuring the whole rig and not just the sails. Having the sails pre-stamped as official wouldn't make any difference as it's the whole rig that needs measuring for the Marblehead class. Same for several other classes.
From experience when measuring a skippers new set of sails, the biggest fault I find is not in the sails themselves, but in how they have not been put on the mast and booms correctly for their measurement bands. Also at this stage as a measurer you take a quick glance over the whole boat and point anything out that has been changed or replaced incorrectly over time.
There's more to measuring than just using a tape measure on the sails.