All 48 peaks on the AMC white mountains 4000-footers¹ list in one continuous trek (no driving/shuttling/etc between trailheads).

¹ this list is outdated vis-a-vis modern mapping and includes at least one peak shorter than 4000 feet (Tecumseh) and omits at least one peak that should qualify per the rules (Guyot), but if the list were updated they would still have completed the direttissima, since they passed over Guyot on the way to the Bonds (dropping Tecumseh could only make the diretissima easier, but I'm not sure it makes much of a difference; it's been a decade or so since I hiked that section of the whites).

As an aside, that day 5 from Wildcat to Cabot is absolutely brutal even if you're fresh, to say nothing of having already covered 180 miles in the previous four days.