It's not often that I first hear of a fell running achievement in the national news, but on BBC Radio 4's Six o'clock news today it was reported that Pawel Cymbalista has just done a set of 7 hill reps with 1343m of climbing and descent in 20 hours and 40 minutes. See https://www.bbc.co.uk/news/articles/crggg1mlvxdo . Presumably he is training for a run from sea level to the top of Everest (a bit less than 7x1343m of climbing), although apparently it's more difficult to fight your way through the crowds of walkers on Everest than on Yr Wyddfa.