I heard about this guy who has done a "vertical marathon" the other day - 223 reps of Pendle Hill from the Barley side in a bit less than 5 days. Completely mind boggling.
Just one everesting on a bike is hard - on foot it must be much harder because of the descent (where on a bike you can at least rest your legs a bit). Can't imagine how hard it would be to do nearly 5 Everests. And in October when quite a bit of it would have been in darkness.
Not a very well laid out article, but gives you a bit more detail.
https://www.thetelegraphandargus.co.uk/news/23060604.anaesthetist-carries-vertical-195-mile-marathon-pendle-hill/
His Strava breaks it down into 4 x Everests + the extra bit to get to 42km vertical:
https://www.strava.com/activities/7933353044
https://www.strava.com/activities/7938485415
https://www.strava.com/activities/7943527503
https://www.strava.com/activities/7955709715
https://www.strava.com/activities/7954723293
Also should have said he was raising money for a charity that supports people affected by Covid: https://www.justgiving.com/fundraising/verticalmarathon