Finalists since I started watching in 2016:
2016 Ore, Danny and Louise.
Will Young withdrew early in the competition.
2017 Alexandra Burke, Debbie McGee, Gemma Atkinson and Joe McFadden.
No withdrawals this year.
2018 Stacey Dooley, Joe Sugg, Ashley Roberts amd Faye Tozer.
No withdrawals this year.
2019 Kelvin Fletcher (replaced Jamie Laing after he sustained an injury at the launch show), Karim Zerol amd Emma Barton.
Will Bailey withdrew due to a injury after a jump in rehearsal.
2020 COVID year.
HRVY, Maisie Smith, Bill Bailey, Jamie Laing
Reduced number of contestants, Nicola Adams also had to withdraw early due to COVID. If she was still in, there would have been a 5 person final, as a couple was eliminated in the week they withdrew. Either that, or Strictly finished a week early!
2021 Rose Ayling Ellis and John Waite were the only finalists since Robert Webb withdrew after week 3 and AJ sustained a leg injury before the final.
2022 Hamzah, Helen Skelton, Mollie Rainford and Fleur East.
No withdrawals.
2023 Ellie Leach, Layton Williams amd Bobbie Brazier.
Nigel Harman withdrew just before Musicals week and Amanda Abbington withdrew after week 4.
There have been a lot of withdrawals which would be why a 3 person final seems like the norm!