3-2-1 is most definately overkill for competition.
The 1/2" pull back from the bone is a good indicator. I think after a while you just tend to know. I cook St. Louis spares in competition and they normally take about 5 hours, but they have been ready as quick as three hours. Probably different from most people, I never wrap my ribs in competition. I do also finish my ribs on a hot grill for 15-30 minutes.
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