"Cave Dog" Ted Keizer established a stout record for climbing all the 4000ers of 3d17h21m, August 9-12, 2002. Cave Dog's site lays out a set of rules for the trip which included no set route, allowance for resupply at any point, and that the clock would start at the first trailhead, and stop at the summit of the last peak. Also, Mt. Washington must be climbed on foot (not using the road or cog railway). These apparently reflect the accepted rules for this venture.
3d 17h 21m