Competive excellence requires 100% all the time. If you doubt that, try maintaining excellence by setting your standards at 92%. Or even 95%. People figure they're doing fine so long as they get somewhere near it. Then things start to happen.
Excellence gets reduced to Acceptable, and before long, acceptable doesn't seem worth the sweat if you can get by with Adequate. After that, Mediocrity is only a breath away.
What would happen if 99.9% were considered good enough?
If that were true, then this year alone .... 2,000,000 doucments would be lost by the IRS.
12 babies would be given to the wrong parents, each day!
291 pacemaker operations would be performed incorrectly.
20,000 incorrect drug prescriptions would be written.