https://vtdigger.org/2024/10/20/then-again-the-long-fast-trail/
https://vtdigger.org/2024/11/03/then-again-treasuring-the-trail/
It turns out that one of the very first people to hike the Long Trail was involved greatly in the history of speed records on the trail. This fantastic article shows how there was a huge tension between "stopping and smelling the roses" and going fast, even back then. Appleby was accompanied for a part of his hike, making it supported. He actually completed the trail a year earlier in about 14 days, but it is unclear what his exact time was or what the start/finish days were, so I elected to not submit that time as it's own FKT.
Appleby claimed his time to be 10 days 10 hours, however he subtracted time where he had to get off trail to tend to his sick compatriot. What we know for certain is that it is documented that he began at "first light" on July 2, 1927 and ended at approximately 8pm on July 14th. In Vermont, first light on July 2nd is at approximately 4:39am. Taking these start and finish times, this imputes a true elapsed time of 12 days, 15 hours, 21 minutes.
There is a ton of great stuff in these two articles, and I highly recommend the read if you're interested in the history of the Long Trail! The history of speed on the Long Trail goes quite far.