I agree a time limit would be good - maybe a week, max. But still, how can it be enforced? How about putting more lenses in circulation, say 3? Of course, there's a high probability some of those will fall into a 'black hole', too. But at least there's a chance we could make it through the list in our lifetimes
. Just need a few willing donors.
Another thought - what about screening the participants somehow - like they'll need at least 500 posts here at PF.com to qualify? That would weed out the 'drive-by' forum members.
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