On Saturday, November 28, 2020, I ran Thunderbolt following the trail description that Drew Best shows on your site. I had scouted out a few turns as my 'warm-up' so I knew where to go on the few unmarked turns. This is a fun but brutal way to climb Greylock. Due to some recent rain, the trail was muddy (which caused a few areas where I took one step up only to slide back down to where I started), so I think this time could certainly be faster in drier conditions. The entire AT section was a mud-pit and it was impossible to dodge the mud pits and fellow hikers (especially while trying to maintain social distancing).
It started snowing about 2/3rd of the way up, which just added a bit of magic to the run. Unfortunately, that meant that there was no view at the top.
Similar to Drew's watch, I recorded a total distance of 2.18 miles. I did take one wrong turn, but only added a hundredth or two to the total distance.