The 2nd season debate rumbles on, so yours truly did a bit of Sherlocking.
Of the 42 clubs promoted from the Championship to the Prem in the period 2007/08 to the end of the 21/22 season....17 were relegated after one season = 40.4%
From the start 2007/08 to the end of the 20/21 season 6 were relegated after the 2nd season: City x2, Birmingham, QPR, Huddersfield, Sheff Utd = 25%
2 were relegated after three seasons...Wolves and Norwich.
0 after four seasons
2 after five seasons...Bmouth and Watford
Burnley had six seasons in the prem...Swansea had seven...WBA had eight...Stoke had ten.
Therefore from this simple analysis its harder to stay in the Prem league for one season than two. What does it prove? Probably not a lot other than I've got too much free time on my hands.